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Questions and Answers
What is the relationship between resistance (R), voltage (V), and current (I) in a circuit?
What is the relationship between resistance (R), voltage (V), and current (I) in a circuit?
- R = V * I
- R = I / V
- R = V / I (correct)
- V = R / I
Which of the following is the correct SI unit for resistance?
Which of the following is the correct SI unit for resistance?
- Volt (V)
- Ampere (A)
- Watt (W)
- Ohm (Ω) (correct)
According to Ohm's Law, for a metallic conductor at a constant temperature, what is the relationship between the current flowing through it and the potential difference across it?
According to Ohm's Law, for a metallic conductor at a constant temperature, what is the relationship between the current flowing through it and the potential difference across it?
- The current is directly proportional to the potential difference. (correct)
- The current is directly proportional to the square of the potential difference.
- The current is inversely proportional to the potential difference.
- The current is independent of the potential difference.
What distinguishes ohmic conductors from non-ohmic conductors?
What distinguishes ohmic conductors from non-ohmic conductors?
If a resting neuron has a potential difference of 70 mV and carries a current of 0.23 mA, what is its resistance?
If a resting neuron has a potential difference of 70 mV and carries a current of 0.23 mA, what is its resistance?
During an action potential, the voltage across a neuron is 30 mV and the resistance is 3.3 kΩ. Approximately how many Na+ ions pass across the neuron in 10 ms, given that the proton charge is $1.6 \times 10^{-19}$ C?
During an action potential, the voltage across a neuron is 30 mV and the resistance is 3.3 kΩ. Approximately how many Na+ ions pass across the neuron in 10 ms, given that the proton charge is $1.6 \times 10^{-19}$ C?
How would you measure the resistance of a component that is not in a working circuit?
How would you measure the resistance of a component that is not in a working circuit?
What are the two primary ways a current can be reduced in a circuit, assuming Ohm's Law applies?
What are the two primary ways a current can be reduced in a circuit, assuming Ohm's Law applies?
If three resistors with resistances R1 = 10Ω, R2 = 20Ω, and R3 = 30Ω are connected in series, what is the total equivalent resistance?
If three resistors with resistances R1 = 10Ω, R2 = 20Ω, and R3 = 30Ω are connected in series, what is the total equivalent resistance?
If three resistors with resistances R1 = 10Ω, R2 = 20Ω and R3 = 30Ω are connected in parallel, what is the total equivalent resistance?
If three resistors with resistances R1 = 10Ω, R2 = 20Ω and R3 = 30Ω are connected in parallel, what is the total equivalent resistance?
A circuit contains three identical light bulbs, A, B, and C, each with a resistance of 15Ω. Bulbs A and B are in series, and this series combination is in parallel with bulb C. What is the total resistance of the circuit?
A circuit contains three identical light bulbs, A, B, and C, each with a resistance of 15Ω. Bulbs A and B are in series, and this series combination is in parallel with bulb C. What is the total resistance of the circuit?
A circuit contains three identical light bulbs, A, B, and C, each with a resistance of 15Ω. Bulbs A and B are in series, and this series combination is in parallel with bulb C. If the battery is 15V, what is the current flowing through the path with the battery and bulb C?
A circuit contains three identical light bulbs, A, B, and C, each with a resistance of 15Ω. Bulbs A and B are in series, and this series combination is in parallel with bulb C. If the battery is 15V, what is the current flowing through the path with the battery and bulb C?
In the same circuit of three identical light bulbs, A, B, and C, each with a resistance of 15Ω, with bulbs A and B in series and this combination in parallel with bulb C. If the battery provides 15V, what is the power consumed by bulb C?
In the same circuit of three identical light bulbs, A, B, and C, each with a resistance of 15Ω, with bulbs A and B in series and this combination in parallel with bulb C. If the battery provides 15V, what is the power consumed by bulb C?
Which of the following factor does not directly affect the resistance of a conductor?
Which of the following factor does not directly affect the resistance of a conductor?
How does increasing the temperature typically affect the resistance of a metallic conductor?
How does increasing the temperature typically affect the resistance of a metallic conductor?
How does increasing the temperature affect the number of free electrons in semiconductors?
How does increasing the temperature affect the number of free electrons in semiconductors?
How does increasing the cross-sectional area of a conductor typically affect its resistance?
How does increasing the cross-sectional area of a conductor typically affect its resistance?
What happens to the resistance of a conductor as its length increases, assuming all other factors remain constant?
What happens to the resistance of a conductor as its length increases, assuming all other factors remain constant?
Given the resistivity of human body is 5.0 Ω.m and copper is $1.7 \times 10^{-8}$ Ω.m. Which material will provide greater resistance and why?
Given the resistivity of human body is 5.0 Ω.m and copper is $1.7 \times 10^{-8}$ Ω.m. Which material will provide greater resistance and why?
A nerve fiber has a diameter of $1 \times 10^{-5}$ m and a resistivity of 2 Ω.m. What is the resistance of a 0.3 m long fiber?
A nerve fiber has a diameter of $1 \times 10^{-5}$ m and a resistivity of 2 Ω.m. What is the resistance of a 0.3 m long fiber?
What formula is used to determine series resistance?
What formula is used to determine series resistance?
What formula is used to determine parallel resistance?
What formula is used to determine parallel resistance?
Which of these statements best defines 'resistance' in the context of electrical circuits?
Which of these statements best defines 'resistance' in the context of electrical circuits?
In an Ohmic resistor, if the voltage across the resistor is doubled, what happens to the resistance, assuming the temperature remains constant?
In an Ohmic resistor, if the voltage across the resistor is doubled, what happens to the resistance, assuming the temperature remains constant?
What effect does increased temperature have on insulators?
What effect does increased temperature have on insulators?
What is the proper formula for calculating power?
What is the proper formula for calculating power?
You have a circuit with a voltage of 12V and a resistance of 4 Ohms. What is the power?
You have a circuit with a voltage of 12V and a resistance of 4 Ohms. What is the power?
You have a circuit with a battery and a single resistor. If you replace the single resistor with three of the same resistors in series, what will happen to the power?
You have a circuit with a battery and a single resistor. If you replace the single resistor with three of the same resistors in series, what will happen to the power?
You have a circuit with a battery and a single resistor. If you replace the single resistor with three of the same resistors in parallel, what will happen to the power?
You have a circuit with a battery and a single resistor. If you replace the single resistor with three of the same resistors in parallel, what will happen to the power?
A wire of length L and cross-sectional area A has a resistance R. If the length is cut in half and the cross-sectional area is doubled, what is the new resistance?
A wire of length L and cross-sectional area A has a resistance R. If the length is cut in half and the cross-sectional area is doubled, what is the new resistance?
What generally happens to resistance as a conductor's diameter shrinks?
What generally happens to resistance as a conductor's diameter shrinks?
What generally happens to resistance as a conductor's diameter grows?
What generally happens to resistance as a conductor's diameter grows?
Flashcards
Define 'Resistance'
Define 'Resistance'
The ratio of potential difference (Volts) across a conductor to the current (Amperes) flowing through it.
What is Ohm's Law?
What is Ohm's Law?
For certain conductors (mainly metals), at constant temperature, the current flowing through them is directly proportional to the potential difference across them.
What are Ohmic Conductors?
What are Ohmic Conductors?
Conductors that obey Ohm's Law, where resistance remains constant as voltage changes.
What are Non-Ohmic Conductors?
What are Non-Ohmic Conductors?
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What are Resistors?
What are Resistors?
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Resistors in series
Resistors in series
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Resistors in parallel
Resistors in parallel
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Factors affecting resistance
Factors affecting resistance
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How does temperature affect conductor resistance?
How does temperature affect conductor resistance?
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How does temperature affect semiconductor or insulator resistance?
How does temperature affect semiconductor or insulator resistance?
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How does cross-sectional area affect resistance?
How does cross-sectional area affect resistance?
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How does length affect resistance?
How does length affect resistance?
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What is Resistivity?
What is Resistivity?
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Study Notes
- Resistance is the ratio of potential difference (Volts) to current (Ampere) in a conductor.
- The SI unit for resistance is the Ohm (Ω).
- The formula for resistance is R = V/I, where R is resistance, V is voltage, and I is current.
- Resistance measures how much current flows with an applied voltage.
- Generally, increasing the applied voltage across a conductor increases the current through it.
Ohm's Law
- Ohm's Law states that for certain conductors (mainly metals) at a constant temperature, the current is directly proportional to the potential difference.
- V = IR, where V is voltage, I is current, and R is resistance.
- The constant of proportionality in Ohm's Law is the resistance (R).
- Ohmic conductors obey Ohm's Law, meaning resistance remains constant when voltage changes; metals and some liquids are examples.
- Non-ohmic conductors' resistance changes with differing potential across them.
Power Equations
- Power (P) can be calculated using the formula P = IV.
- Using Ohm's Law (V = IR), power can also be expressed as P = I²R or P = V²/R.
Calculating Resistance
- To find the resistance, measure the current and voltage, then apply Ohm's Law.
- An ohmmeter measures the resistance of a conductor or circuit element when it's not in a working circuit.
- A resistor is an electronic component implementing electrical resistance in a circuit.
Resistors
- Applying voltage V across a resistor results in a current I flowing through it, directly proportional to the voltage.
- To reduce current in a circuit to a specific level, voltage can be reduced, or resistance increased.
Resistors in Series and Parallel
- For resistors in series, the total resistance (Rtot) is the sum of individual resistances: Rtot = R1 + R2 + R3 + R4.
- For resistors in parallel, the reciprocal of the total resistance is the sum of the reciprocals of individual resistances: 1/Rtot = 1/R1 + 1/R2 + 1/R3.
Factors Affecting Resistance
- Four factors affect the resistance of a conductor: temperature, length, cross-sectional area, and material.
Temperature Effects
- In conductors, electrons are free, and as temperature rises in metallic conductors, atoms vibrate more, leading to more electron collisions with fixed atoms.
- In insulators, electrons do not flow easily; semiconductors allow electron flow more than insulators but less than conductors due to electron attachment to atoms.
- With increased temperature, fixed atoms vibrate more, causing electrons to "break free" and form a current; increased free electrons affect resistance more than the vibration of fixed atoms.
Cross-Sectional Area
- A larger cross-sectional area allows more electrons to pass per unit of time due to reduced friction, decreasing resistance. As cross-sectional area increases, resistance decreases.
Length
- The longer the conductor, the more collisions electrons undergo with fixed atoms, thus increasing resistance. Resistance increases as length increases.
Material
- Different materials have varying resistivity based on their electronic structure and temperature.
- Human body resistivity is 5.0 Ω.m, while copper's is 1.7 x 10-8 Ω.m.
Resistivity
- Resistivity (ρ) measures how much a material opposes current flow.
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