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Questions and Answers
In a metallic conductor, what is primarily responsible for the flow of electric current?
In a metallic conductor, what is primarily responsible for the flow of electric current?
- The flow of protons from the positive to the negative terminal.
- The drift of free electrons opposite to the direction of the electric field. (correct)
- The movement of positive ions in the direction of the electric field.
- The vibration of atoms within the metal lattice.
Why is it important to understand the distinction between conventional current and electron flow?
Why is it important to understand the distinction between conventional current and electron flow?
- Because circuit analysis techniques differ based on whether you use conventional current or electron flow.
- Because electron flow determines the direction of magnetic fields, while conventional current does not.
- It's a historical convention, and using either concept yields the same results in circuit analysis. (correct)
- Because the direction of electron flow affects the polarity of circuit components.
A circuit has a voltage of 12V and a resistance of 4 ohms. If the resistance is doubled, what is the new current, assuming the voltage remains constant?
A circuit has a voltage of 12V and a resistance of 4 ohms. If the resistance is doubled, what is the new current, assuming the voltage remains constant?
- 3A
- 6A
- 1.5A (correct)
- 4A
How does electrical power relate to voltage, current, and resistance in a circuit?
How does electrical power relate to voltage, current, and resistance in a circuit?
Which of the following is the correct representation of a resistor in a circuit diagram?
Which of the following is the correct representation of a resistor in a circuit diagram?
How does the resistance of a typical light bulb filament change as it heats up when the current flows?
How does the resistance of a typical light bulb filament change as it heats up when the current flows?
What distinguishes an NTC thermistor from a PTC thermistor?
What distinguishes an NTC thermistor from a PTC thermistor?
An LDR is used in a circuit to automatically turn on a street light at night. How does the LDR's resistance change as darkness falls?
An LDR is used in a circuit to automatically turn on a street light at night. How does the LDR's resistance change as darkness falls?
In a series circuit with three resistors, if one resistor fails (opens), what happens to the current in the circuit?
In a series circuit with three resistors, if one resistor fails (opens), what happens to the current in the circuit?
In a parallel circuit, what remains the same across each branch?
In a parallel circuit, what remains the same across each branch?
Two resistors, 6 ohms and 12 ohms, are connected in series with a 9V battery. What is the current flowing through the circuit?
Two resistors, 6 ohms and 12 ohms, are connected in series with a 9V battery. What is the current flowing through the circuit?
Three resistors, 10 ohms, 20 ohms, and 30 ohms, are connected in parallel. What is the total resistance of the parallel combination?
Three resistors, 10 ohms, 20 ohms, and 30 ohms, are connected in parallel. What is the total resistance of the parallel combination?
In a series circuit with two resistors, $R_1$ and $R_2$, if $R_1$ has a larger resistance than $R_2$, which resistor will have a larger voltage drop across it?
In a series circuit with two resistors, $R_1$ and $R_2$, if $R_1$ has a larger resistance than $R_2$, which resistor will have a larger voltage drop across it?
In a parallel circuit with three branches, each having different resistances, which branch will draw the most current?
In a parallel circuit with three branches, each having different resistances, which branch will draw the most current?
How does increasing the temperature of a typical metallic conductor affect its resistance?
How does increasing the temperature of a typical metallic conductor affect its resistance?
If two voltage sources are connected in series with opposing polarities, what is the total voltage?
If two voltage sources are connected in series with opposing polarities, what is the total voltage?
What happens to the total resistance of a parallel circuit as more resistors are added in parallel?
What happens to the total resistance of a parallel circuit as more resistors are added in parallel?
A circuit contains a 10-ohm resistor with a current of 2A flowing through it. What is the power consumed by the resistor?
A circuit contains a 10-ohm resistor with a current of 2A flowing through it. What is the power consumed by the resistor?
How does understanding circuit diagrams aid in circuit analysis?
How does understanding circuit diagrams aid in circuit analysis?
In a parallel circuit consisting of a 5-ohm and a 10-ohm resistor connected to a 10V source, what is the current flowing through the 5-ohm resistor?
In a parallel circuit consisting of a 5-ohm and a 10-ohm resistor connected to a 10V source, what is the current flowing through the 5-ohm resistor?
Flashcards
Free Electrons in Metals
Free Electrons in Metals
Metals have a lattice of positive ions in a sea of mobile electrons, which move freely allowing electrical conduction.
How Conduction Works
How Conduction Works
When voltage is applied to a metal, free electrons drift from negative to positive, creating electric current.
Conventional Current
Conventional Current
Current flows from positive to negative, historically defined this way.
Electron Flow
Electron Flow
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Ohm's Law
Ohm's Law
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Electrical Power
Electrical Power
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Circuit Diagrams
Circuit Diagrams
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Light Bulb Resistance
Light Bulb Resistance
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NTC Thermistor
NTC Thermistor
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PTC Thermistor
PTC Thermistor
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LDR (Light Dependent Resistor)
LDR (Light Dependent Resistor)
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Current in Series Circuits
Current in Series Circuits
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Voltage in Series Circuits
Voltage in Series Circuits
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Resistance in Series Circuits
Resistance in Series Circuits
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Combined Voltage Sources (Series)
Combined Voltage Sources (Series)
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Current in Parallel Circuits
Current in Parallel Circuits
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Voltage in Parallel Circuits
Voltage in Parallel Circuits
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Resistance in Parallel Circuits
Resistance in Parallel Circuits
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Potential Drops in Series
Potential Drops in Series
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Potential Drops in Parallel
Potential Drops in Parallel
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Study Notes
- Metals contain positive ions in a lattice structure surrounded by free electrons.
- Free electrons enable metals to conduct electricity effectively due to their mobility.
How Conduction Works
- Applying a voltage to a metal causes free electrons to drift towards the positive potential, creating electric current.
- Conventional current is defined as flowing from positive to negative, which is opposite to the direction of electron flow.
Conventional Current vs. Electron Flow
- Conventional current flows from the positive terminal to the negative terminal.
- Electrons flow from the negative terminal to the positive terminal.
- The difference between conventional current and electron flow does not impact circuit analysis.
Ohm’s Law
- Current through a conductor is proportional to voltage and inversely proportional to resistance: V=I×R.
- Increasing resistance decreases current if voltage is constant.
- Increasing voltage increases current if resistance is constant.
Electrical Power in Circuits
- Power is calculated as P=V×I, or alternatively as P=I2×R or P=V2/R.
- Power indicates the rate of electrical energy conversion into other forms of energy.
Circuit Diagrams
- Resistors are represented by a zig-zag line in circuit diagrams.
- Batteries are represented by lines of differing lengths, with longer line indicating the positive terminal.
- Circuit diagrams help visualize component connections and aid in analyzing current flow and voltage drops.
Variation of Resistance
- Light bulb filament resistance increases as temperature increases.
- NTC thermistors decrease resistance as temperature increases.
- PTC thermistors increase resistance as temperature increases.
- LDR resistance decreases as light intensity increases.
Series Circuits
- The current is the same through all components.
- Total voltage is divided among components: Vtotal=V1+V2+...+Vn.
- Total resistance is the sum of individual resistances: Rtotal=R1+R2+...+Rn.
- Voltage sources add together when connected in series.
Parallel Circuits
- Total current is divided among different branches.
- Each branch experiences the same voltage as the source.
- The reciprocal of total resistance equals the sum of reciprocals of individual resistances: 1/Rtotal=1/R1+1/R2+...+1/Rn.
- Voltage is equal across all components.
Series Circuits Calculations
- Voltage drop across each resistor is Vi=I×Ri.
- Total resistance is Rtotal=R1+R2+...+Rn.
- Total voltage with multiple sources is Vtotal=V1+V2+...+Vn.
Parallel Circuits Calculations
- The formula 1/Rtotal=1/R1+1/R2+...+1/Rn is used to find total resistance.
- Current in each branch is Ii=V/Ri.
- The voltage drop across each branch equals the source voltage.
Summary
- Free electrons under voltage result in current, opposite to the conventional current direction.
- V=I×R governs circuit behavior; power is calculated using voltage, current, or resistance.
- Circuit diagrams help visualize circuit connections.
- Resistance changes in light bulbs, thermistors, and LDRs under different conditions influence circuit behavior.
- Series circuits share the same current with divided voltage, while parallel circuits have equal voltage across branches with divided current.
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