Podcast
Questions and Answers
What is the relationship between current, voltage, and resistance as described by Ohm's Law?
What is the relationship between current, voltage, and resistance as described by Ohm's Law?
- Current is directly proportional to voltage and inversely proportional to resistance.
- Voltage is directly proportional to current and resistance.
- Resistance is directly proportional to voltage and inversely proportional to current.
- All of the above. (correct)
What distinguishes an ohmic conductor from a nonohmic conductor?
What distinguishes an ohmic conductor from a nonohmic conductor?
- Ohmic conductors are always semiconductors, while nonohmic conductors are always metals.
- Nonohmic conductors have a linear voltage-current relationship; ohmic conductors do not.
- Nonohmic conductors obey Ohm's Law, while ohmic conductors do not.
- Ohmic conductors have a constant resistance regardless of temperature; nonohmic conductors do not. (correct)
In a series circuit, what remains the same across all components?
In a series circuit, what remains the same across all components?
- Power
- Resistance
- Current (correct)
- Voltage
What is the formula for calculating total resistance in a parallel circuit?
What is the formula for calculating total resistance in a parallel circuit?
If you have a circuit with two resistors in parallel, and that combination is in series with another resistor, how would you calculate the total resistance?
If you have a circuit with two resistors in parallel, and that combination is in series with another resistor, how would you calculate the total resistance?
What is the basic formula for calculating electrical power in a circuit?
What is the basic formula for calculating electrical power in a circuit?
Which of the following equations correctly relates power, current, and resistance?
Which of the following equations correctly relates power, current, and resistance?
If you know the voltage across a circuit element and its resistance, which formula would you use to calculate power?
If you know the voltage across a circuit element and its resistance, which formula would you use to calculate power?
What unit is used to measure electrical energy?
What unit is used to measure electrical energy?
How is electrical energy consumption typically measured for household billing purposes?
How is electrical energy consumption typically measured for household billing purposes?
What is the formula to calculate the cost of running an electrical appliance?
What is the formula to calculate the cost of running an electrical appliance?
A hair dryer is rated at 1500 W. If you use it for 20 minutes, how many kilowatthours of energy does it consume?
A hair dryer is rated at 1500 W. If you use it for 20 minutes, how many kilowatthours of energy does it consume?
How does increasing the resistance in a circuit affect the current, assuming the voltage remains constant?
How does increasing the resistance in a circuit affect the current, assuming the voltage remains constant?
A circuit contains a 10-ohm resistor and a 20-ohm resistor in series. If a 9V battery is connected across the circuit, what is the current flowing through the 10-ohm resistor?
A circuit contains a 10-ohm resistor and a 20-ohm resistor in series. If a 9V battery is connected across the circuit, what is the current flowing through the 10-ohm resistor?
A parallel circuit has three resistors with resistances of 2 ohms, 4 ohms, and 8 ohms. What is the total equivalent resistance of the circuit?
A parallel circuit has three resistors with resistances of 2 ohms, 4 ohms, and 8 ohms. What is the total equivalent resistance of the circuit?
A light bulb is connected to a 120V source and draws a current of 0.5A. If the cost of electricity is $0.10 per kWh, what is the cost of running the bulb for 24 hours?
A light bulb is connected to a 120V source and draws a current of 0.5A. If the cost of electricity is $0.10 per kWh, what is the cost of running the bulb for 24 hours?
A device has a power rating of 100 W. How much energy does it consume in 2 minutes?
A device has a power rating of 100 W. How much energy does it consume in 2 minutes?
Which of the following materials would be classified as a nonohmic conductor?
Which of the following materials would be classified as a nonohmic conductor?
What happens to the power dissipated by a resistor if both the current through it and the voltage across it are doubled?
What happens to the power dissipated by a resistor if both the current through it and the voltage across it are doubled?
Two resistors, one with a resistance of $R$ and the other with a resistance of $2R$, are connected in parallel to a voltage source $V$. What is the ratio of the current through the resistor with resistance $R$ to the current through the resistor with resistance $2R$?
Two resistors, one with a resistance of $R$ and the other with a resistance of $2R$, are connected in parallel to a voltage source $V$. What is the ratio of the current through the resistor with resistance $R$ to the current through the resistor with resistance $2R$?
A 100-ohm resistor is connected in series with a device that draws a current described by $I(t) = 0.5sin(2\pi{}t)$ amps, where t is time in seconds. What is the average power dissipated across the resistor over a long period?
A 100-ohm resistor is connected in series with a device that draws a current described by $I(t) = 0.5sin(2\pi{}t)$ amps, where t is time in seconds. What is the average power dissipated across the resistor over a long period?
A complex circuit is constructed with multiple series and parallel combinations of resistors. Without knowing the exact values, if you increase the resistance of every resistor in the circuit, how will the current supplied by the voltage source change, assuming the voltage remains constant?
A complex circuit is constructed with multiple series and parallel combinations of resistors. Without knowing the exact values, if you increase the resistance of every resistor in the circuit, how will the current supplied by the voltage source change, assuming the voltage remains constant?
A parallel plate capacitor with initial voltage $V_0$ is discharged through a resistor $R$. The current $I(t)$ at time $t$ is given by $I(t) = (V_0/R)e^{-t/RC}$. What is the total energy dissipated in the resistor over an infinite amount of time?
A parallel plate capacitor with initial voltage $V_0$ is discharged through a resistor $R$. The current $I(t)$ at time $t$ is given by $I(t) = (V_0/R)e^{-t/RC}$. What is the total energy dissipated in the resistor over an infinite amount of time?
In a purely theoretical circuit, a 'negative resistor' is introduced. Negative resistance means that as current increases, voltage decreases (V = -IR, where R is a positive number). If such a component were wired in parallel with a normal resistor and connected to a voltage source, what might occur?
In a purely theoretical circuit, a 'negative resistor' is introduced. Negative resistance means that as current increases, voltage decreases (V = -IR, where R is a positive number). If such a component were wired in parallel with a normal resistor and connected to a voltage source, what might occur?
What is the fundamental relationship that Ohm's Law describes?
What is the fundamental relationship that Ohm's Law describes?
According to Ohm's Law, what happens to the current flowing through a conductor if the voltage across it is doubled while the resistance remains constant?
According to Ohm's Law, what happens to the current flowing through a conductor if the voltage across it is doubled while the resistance remains constant?
What characteristic defines an ohmic conductor?
What characteristic defines an ohmic conductor?
Which of the following is an example of a nonohmic conductor?
Which of the following is an example of a nonohmic conductor?
In a series circuit with three resistors, if one resistor's value increases, what happens to the total resistance of the circuit?
In a series circuit with three resistors, if one resistor's value increases, what happens to the total resistance of the circuit?
In a parallel circuit, how does the voltage across each component compare?
In a parallel circuit, how does the voltage across each component compare?
For a circuit containing both series and parallel resistors, what is the general strategy for calculating the total resistance?
For a circuit containing both series and parallel resistors, what is the general strategy for calculating the total resistance?
Which of the following represents the correct formula for calculating electrical power?
Which of the following represents the correct formula for calculating electrical power?
If a resistor has a voltage $V$ across it and a current $I$ flowing through it, how would you calculate the power dissipated by the resistor?
If a resistor has a voltage $V$ across it and a current $I$ flowing through it, how would you calculate the power dissipated by the resistor?
Given a constant resistance, how does the power dissipated change if the voltage is tripled?
Given a constant resistance, how does the power dissipated change if the voltage is tripled?
What unit is used to measure electrical energy consumption?
What unit is used to measure electrical energy consumption?
What is the formula to calculate the total electrical energy consumed by a device?
What is the formula to calculate the total electrical energy consumed by a device?
A 2 kW electric heater is used for 30 minutes. How much energy does it consume in kilowatthours?
A 2 kW electric heater is used for 30 minutes. How much energy does it consume in kilowatthours?
If the cost of electricity is $0.15 per kWh, what is the cost of running a 100W light bulb for 10 hours?
If the cost of electricity is $0.15 per kWh, what is the cost of running a 100W light bulb for 10 hours?
How does decreasing the voltage applied to a circuit (with constant resistance) affect the power dissipated?
How does decreasing the voltage applied to a circuit (with constant resistance) affect the power dissipated?
A series circuit consists of a 6-ohm resistor and an unknown resistor. If the current through the 6-ohm resistor is 2A and the total voltage across the circuit is 24V, what is the value of the unknown resistor?
A series circuit consists of a 6-ohm resistor and an unknown resistor. If the current through the 6-ohm resistor is 2A and the total voltage across the circuit is 24V, what is the value of the unknown resistor?
A 120V supply is connected to a heating element with a resistance of 10 ohms. Determine the power consumed by the heating element.
A 120V supply is connected to a heating element with a resistance of 10 ohms. Determine the power consumed by the heating element.
What characteristic definitively identifies a nonohmic resistor?
What characteristic definitively identifies a nonohmic resistor?
By what factor does the power dissipated in a resistor change if the current through it is halved?
By what factor does the power dissipated in a resistor change if the current through it is halved?
Two resistors, $R_1$ and $R_2$ (with $R_2 = 3R_1$), are connected in parallel across a voltage source. What is the ratio of the current through $R_1$ to the current through $R_2$?
Two resistors, $R_1$ and $R_2$ (with $R_2 = 3R_1$), are connected in parallel across a voltage source. What is the ratio of the current through $R_1$ to the current through $R_2$?
A real-world power supply provides a fixed voltage, but also has an internal resistance. If you connect a very low resistance load to this power supply, what will happen?
A real-world power supply provides a fixed voltage, but also has an internal resistance. If you connect a very low resistance load to this power supply, what will happen?
A circuit is mistakenly wired such that a 10-ohm resistor is placed in parallel with a 100 $\mu$F capacitor. A 10V DC source is then connected to this parallel combination. After a long time, what is the current flowing through the resistor?
A circuit is mistakenly wired such that a 10-ohm resistor is placed in parallel with a 100 $\mu$F capacitor. A 10V DC source is then connected to this parallel combination. After a long time, what is the current flowing through the resistor?
Imagine a scenario where electricity costs decrease linearly with usage due to a government subsidy program. If the cost per kWh is given by $C(E) = a - bE$, where $E$ is the energy consumed, and $a$ and $b$ are positive constants, how would you calculate your total electricity bill for a consumption of $E_0$ kWh?
Imagine a scenario where electricity costs decrease linearly with usage due to a government subsidy program. If the cost per kWh is given by $C(E) = a - bE$, where $E$ is the energy consumed, and $a$ and $b$ are positive constants, how would you calculate your total electricity bill for a consumption of $E_0$ kWh?
Consider a circuit with a single resistor connected to an AC voltage source. If the frequency of the AC voltage is significantly increased, how does this affect the average power dissipated by the resistor, assuming the RMS voltage remains constant?
Consider a circuit with a single resistor connected to an AC voltage source. If the frequency of the AC voltage is significantly increased, how does this affect the average power dissipated by the resistor, assuming the RMS voltage remains constant?
In a hypothetical scenario, an electrical component is developed such that its resistance decreases as its temperature decreases, following the equation $R(T) = R_0e^{-kT}$, where $R_0$ and $k$ are positive constants, and $T$ is the temperature in Kelvin. If this component is used in a circuit in an environment where the temperature spontaneously drops, what would you expect to observe?
In a hypothetical scenario, an electrical component is developed such that its resistance decreases as its temperature decreases, following the equation $R(T) = R_0e^{-kT}$, where $R_0$ and $k$ are positive constants, and $T$ is the temperature in Kelvin. If this component is used in a circuit in an environment where the temperature spontaneously drops, what would you expect to observe?
Which of the following defines electrical current?
Which of the following defines electrical current?
What is the unit of measurement for electrical resistance?
What is the unit of measurement for electrical resistance?
According to Ohm's Law, if the resistance in a circuit is halved and the voltage remains constant, what happens to the current?
According to Ohm's Law, if the resistance in a circuit is halved and the voltage remains constant, what happens to the current?
Which of the following materials is an example of an ohmic conductor?
Which of the following materials is an example of an ohmic conductor?
In a series circuit, how does the current compare through each resistor?
In a series circuit, how does the current compare through each resistor?
What remains constant across all components in a parallel circuit?
What remains constant across all components in a parallel circuit?
What is the formula for calculating electrical power using current and voltage?
What is the formula for calculating electrical power using current and voltage?
If you double both the voltage across a resistor and the current through it, by what factor does the power dissipated increase?
If you double both the voltage across a resistor and the current through it, by what factor does the power dissipated increase?
Which of the following best describes a nonohmic conductor?
Which of the following best describes a nonohmic conductor?
When resistors are connected in series, the total resistance is:
When resistors are connected in series, the total resistance is:
For resistors in parallel, the reciprocal of the total resistance is equal to:
For resistors in parallel, the reciprocal of the total resistance is equal to:
If a 100W light bulb is left on for 2 hours, how much energy is consumed in kilowatthours (kWh)?
If a 100W light bulb is left on for 2 hours, how much energy is consumed in kilowatthours (kWh)?
A device with a higher power rating will generally:
A device with a higher power rating will generally:
Using Ohm's Law and the power formula, which of the following equations correctly expresses power in terms of voltage and resistance only?
Using Ohm's Law and the power formula, which of the following equations correctly expresses power in terms of voltage and resistance only?
If the voltage across a resistor is tripled, while the resistance remains constant, by what factor does the power dissipated increase?
If the voltage across a resistor is tripled, while the resistance remains constant, by what factor does the power dissipated increase?
Two resistors, one with resistance $R$ and another with resistance $3R$, are connected in parallel. What is the ratio of the current through the resistor $R$ to the current through the resistor $3R$?
Two resistors, one with resistance $R$ and another with resistance $3R$, are connected in parallel. What is the ratio of the current through the resistor $R$ to the current through the resistor $3R$?
A circuit is constructed with a combination of series and parallel resistors. To find the total resistance, you should:
A circuit is constructed with a combination of series and parallel resistors. To find the total resistance, you should:
A heating element consumes 1200 kJ of energy in 10 minutes. What is its power rating in kilowatts?
A heating element consumes 1200 kJ of energy in 10 minutes. What is its power rating in kilowatts?
If the cost of electricity is $0.12 per kWh, what is the cost of running a 200W appliance for 24 hours?
If the cost of electricity is $0.12 per kWh, what is the cost of running a 200W appliance for 24 hours?
Consider a scenario where a light bulb's resistance increases as it heats up. What effect does this have on the current through the bulb as it operates, assuming a constant voltage source?
Consider a scenario where a light bulb's resistance increases as it heats up. What effect does this have on the current through the bulb as it operates, assuming a constant voltage source?
In a purely resistive circuit, if you want to minimize power dissipation while maintaining a constant voltage, you should:
In a purely resistive circuit, if you want to minimize power dissipation while maintaining a constant voltage, you should:
For a given voltage source, which configuration of three identical resistors will result in the highest total current drawn from the source?
For a given voltage source, which configuration of three identical resistors will result in the highest total current drawn from the source?
A circuit contains a nonohmic device. If you plot a graph of voltage versus current for this device, what would be the shape of the graph?
A circuit contains a nonohmic device. If you plot a graph of voltage versus current for this device, what would be the shape of the graph?
If you have a circuit with several resistors in series and you increase the resistance of just one of these resistors, what will happen to the total current in the circuit (assuming constant voltage source)?
If you have a circuit with several resistors in series and you increase the resistance of just one of these resistors, what will happen to the total current in the circuit (assuming constant voltage source)?
Consider a circuit with a voltage source and a resistor. If the voltage of the source is AC instead of DC but the RMS voltage value remains the same, how does the average power dissipated in the resistor change?
Consider a circuit with a voltage source and a resistor. If the voltage of the source is AC instead of DC but the RMS voltage value remains the same, how does the average power dissipated in the resistor change?
What is the fundamental quantity defined as the rate of flow of electric charge?
What is the fundamental quantity defined as the rate of flow of electric charge?
According to Ohm's Law, if you increase the voltage across a resistor in a circuit while keeping the resistance constant, what happens to the current?
According to Ohm's Law, if you increase the voltage across a resistor in a circuit while keeping the resistance constant, what happens to the current?
Which of the following materials is best described as an ohmic conductor?
Which of the following materials is best described as an ohmic conductor?
In a series circuit, how does the magnitude of current compare at different points in the circuit?
In a series circuit, how does the magnitude of current compare at different points in the circuit?
For resistors connected in parallel, what quantity is the same across each resistor?
For resistors connected in parallel, what quantity is the same across each resistor?
What is the formula used to calculate electrical power in a circuit?
What is the formula used to calculate electrical power in a circuit?
If a resistor has a voltage of 12V across it and a current of 2A flowing through it, what is its resistance?
If a resistor has a voltage of 12V across it and a current of 2A flowing through it, what is its resistance?
Three resistors with resistances of 3 ohms, 6 ohms, and 9 ohms are connected in series. What is the total equivalent resistance?
Three resistors with resistances of 3 ohms, 6 ohms, and 9 ohms are connected in series. What is the total equivalent resistance?
Two resistors, 10 ohms and 15 ohms, are connected in parallel. What is their equivalent resistance?
Two resistors, 10 ohms and 15 ohms, are connected in parallel. What is their equivalent resistance?
A light bulb is rated at 60W and operates at 120V. What current does it draw under normal operation?
A light bulb is rated at 60W and operates at 120V. What current does it draw under normal operation?
If the current through a 4-ohm resistor is 3A, what is the power dissipated by the resistor?
If the current through a 4-ohm resistor is 3A, what is the power dissipated by the resistor?
What happens to the total resistance of a series circuit if another resistor is added in series?
What happens to the total resistance of a series circuit if another resistor is added in series?
What happens to the total resistance of a parallel circuit if another resistor is added in parallel?
What happens to the total resistance of a parallel circuit if another resistor is added in parallel?
A 100W light bulb is left on for 10 hours. How much energy in kilowatthours (kWh) is consumed?
A 100W light bulb is left on for 10 hours. How much energy in kilowatthours (kWh) is consumed?
If the voltage across a resistor is doubled, and the resistance is halved, by what factor does the current change?
If the voltage across a resistor is doubled, and the resistance is halved, by what factor does the current change?
A heating element with a resistance of 20 ohms is connected to a 240V supply. What is the power consumed by the heating element?
A heating element with a resistance of 20 ohms is connected to a 240V supply. What is the power consumed by the heating element?
For a nonohmic conductor like a light bulb, as the voltage across it increases, what generally happens to its resistance?
For a nonohmic conductor like a light bulb, as the voltage across it increases, what generally happens to its resistance?
If you want to minimize the power dissipated in a resistor for a given current, what should you do to the resistance?
If you want to minimize the power dissipated in a resistor for a given current, what should you do to the resistance?
Two resistors of equal resistance are connected in parallel. How does their equivalent resistance compare to the resistance of a single resistor?
Two resistors of equal resistance are connected in parallel. How does their equivalent resistance compare to the resistance of a single resistor?
A circuit is constructed with a combination of series and parallel resistors. To find the total resistance, what is the general approach?
A circuit is constructed with a combination of series and parallel resistors. To find the total resistance, what is the general approach?
An electric heater consumes 3 kWh of energy in 2 hours. What is the power rating of the heater in kilowatts?
An electric heater consumes 3 kWh of energy in 2 hours. What is the power rating of the heater in kilowatts?
If the cost of electricity is $0.20 per kWh, what is the cost of running a 1500W appliance for 30 minutes?
If the cost of electricity is $0.20 per kWh, what is the cost of running a 1500W appliance for 30 minutes?
Consider a circuit with resistors in series. If one resistor's value is significantly larger than the others, what will be the approximate voltage drop across it compared to the total voltage?
Consider a circuit with resistors in series. If one resistor's value is significantly larger than the others, what will be the approximate voltage drop across it compared to the total voltage?
In a parallel circuit, if one branch has significantly lower resistance than other branches, what can be said about the current flowing through that branch compared to the total current?
In a parallel circuit, if one branch has significantly lower resistance than other branches, what can be said about the current flowing through that branch compared to the total current?
A device is labeled '120V, 60W'. If it is connected to a 240V source (assuming its resistance remains constant), what power will it dissipate?
A device is labeled '120V, 60W'. If it is connected to a 240V source (assuming its resistance remains constant), what power will it dissipate?
Flashcards
Electrical Current (I)
Electrical Current (I)
The rate of flow of charge through a circuit.
Potential Difference (Voltage, V)
Potential Difference (Voltage, V)
The energy needed to move a unit charge between two points in a circuit.
Resistance (R)
Resistance (R)
A measure of how difficult it is to push current through a circuit element.
Ohm's Law
Ohm's Law
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Ohmic Conductors
Ohmic Conductors
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Ohmic Conductor Characteristics
Ohmic Conductor Characteristics
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Nonohmic Conductors
Nonohmic Conductors
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Series Circuit
Series Circuit
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Total Resistance in Series (Rs)
Total Resistance in Series (Rs)
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Current in Series Circuits
Current in Series Circuits
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Voltage across each resistor
Voltage across each resistor
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Parallel Circuit
Parallel Circuit
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Total Resistance in Parallel (Rp)
Total Resistance in Parallel (Rp)
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Voltage in Parallel Circuits
Voltage in Parallel Circuits
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Total Current in Parallel
Total Current in Parallel
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Electrical Power (P)
Electrical Power (P)
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Basic Power Formula
Basic Power Formula
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Power Formula (using I and R)
Power Formula (using I and R)
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Power Formula (using V and R)
Power Formula (using V and R)
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Electrical Energy (E)
Electrical Energy (E)
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Kilowatt-hour (kWh)
Kilowatt-hour (kWh)
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Watts to Kilowatts
Watts to Kilowatts
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Cost of Electricity
Cost of Electricity
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Chemical Potential Energy
Chemical Potential Energy
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Watt (W)
Watt (W)
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What are ohmic conductors?
What are ohmic conductors?
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What are non-ohmic conductors?
What are non-ohmic conductors?
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What does Ohm's Law describe?
What does Ohm's Law describe?
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What is Power?
What is Power?
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How is the cost of electricity calculated?
How is the cost of electricity calculated?
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Ohm's Law Definition
Ohm's Law Definition
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Voltage in Series Circuits
Voltage in Series Circuits
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Current in Parallel Circuits
Current in Parallel Circuits
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Combining Circuits
Combining Circuits
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Electrical Power Defined
Electrical Power Defined
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Electrical Energy Defined
Electrical Energy Defined
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Power Proportionality
Power Proportionality
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What defines Ohmic Conductors?
What defines Ohmic Conductors?
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What defines non-Ohmic Conductors?
What defines non-Ohmic Conductors?
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What is an equivalent resistance?
What is an equivalent resistance?
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What happens when a resistor gets hot?
What happens when a resistor gets hot?
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How to calculate appliance running cost?
How to calculate appliance running cost?
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Study Notes
Ohm’s Law
- Electrical current (I) measures the rate of charge flow through a circuit.
- Voltage (V) is the energy per unit charge needed to move charge between two points in a circuit.
- Resistance (R) indicates how difficult it is to push current through a circuit element.
- Ohm's Law states ( I = \frac{V}{R} ), where current is proportional to voltage and inversely proportional to resistance at a constant temperature.
- The resistance of a conductor remains constant at a constant temperature, regardless of voltage or current.
- A graph of voltage on the x-axis and current on the y-axis for a conductor at a constant temperature yields a straight line.
- Ohmic conductors obey Ohm’s Law, maintaining constant resistance despite changes in voltage or current; examples include circuit resistors and nichrome wire.
- Nonohmic conductors, such as light bulbs, diodes, and transistors, do not obey Ohm’s Law because their resistance changes with temperature.
- For ohmic conductors, a current vs. voltage graph is linear; for nonohmic conductors, it is not.
- Resistance can be defined as ( R = \frac{V}{I} )
Series Circuits
- Only one path exists for current flow.
- Total resistance is the sum of individual resistances: ( R_s = R_1 + R_2 + R_3 + \ldots + R_n )
- Current remains the same through all components: ( I = I_1 = I_2 = I_3 )
- Voltage across each resistor is proportional to its resistance.
- Total voltage equals the sum of voltages across all resistors: ( V = V_1 + V_2 + V_3 )
Parallel Circuits
- Multiple paths exist for current flow.
- Total resistance is given by: ( \frac{1}{R_p} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + \ldots + \frac{1}{R_n} )
- Voltage is the same across all components: ( V = V_1 = V_2 = V_3 )
- Total current is the sum of currents through each path: ( I = I_1 + I_2 + I_3 )
Combining Series and Parallel Circuits
- Calculate total resistance in stages.
- Find the total resistance of parallel portions first
- Then, add the resistances in series.
Electrical Power
- Electrical power is the rate at which electrical energy is converted in a circuit.
- Basic formula: ( P = I \cdot V ), where power is in watts, current in amperes, and voltage in volts.
- Power is directly proportional to both current and voltage.
- Alternative formula: ( P = I^2 \cdot R ), useful when current and resistance are known.
- Alternative formula: ( P = \frac{V^2}{R} ), useful when voltage and resistance are known.
- Power is measured in watts (W), equivalent to joules per second (J/s).
Electrical Energy
- Energy is transferred when power is dissipated.
- Formula: ( E = P \cdot t ), where energy is in joules, power in watts, and time in seconds.
- Electrical energy is often measured in kilowatt-hours (kWh) for household and commercial purposes.
- 1 kWh equals 1 kW of power used for 1 hour (( 1 \text{ kWh} = 1 \text{ kW} \times 1 \text{ hour} )).
- Batteries convert chemical potential energy into electrical energy
Cost of Electricity
- Calculated by multiplying total energy consumption in kWh by the cost per kWh.
- Cost calculation: ( \text{Cost} = \text{Power (kW)} \times \text{Time (hours)} \times \text{Cost per kWh} )
- To find the cost of running an appliance:
- Determine the appliance's power rating in kilowatts (kW).
- Multiply the power rating by the time in hours the appliance is used.
- Multiply the result by the cost per kilowatthour.
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