B.5 Current and circuits

Show that the current in Q is 0.45 A.

Show that the current in Q is 0.45 A.

Show that the current in Q is 0.45 A.

Show that the current in Q is 0.45 A.

Show that the current in Q is 0.45 A.

Show that the current in Q is 0.45 A.

Calculate the resistance of R.

Calculate the resistance of R.

Calculate the resistance of R.

Calculate the resistance of R.

Calculate the resistance of R.

Calculate the resistance of R.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

Just before the loop is about to completely exit the region of magnetic field, the loop moves with constant terminal speed v.

The following data is available:

Determine, in m s⁻¹ the terminal speed v.

Just before the loop is about to completely exit the region of magnetic field, the loop moves with constant terminal speed v.

The following data is available:

Determine, in m s⁻¹ the terminal speed v.

Just before the loop is about to completely exit the region of magnetic field, the loop moves with constant terminal speed v.

The following data is available:

Determine, in m s⁻¹ the terminal speed v.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.

the pd across the motor of the tram,

the pd across the motor of the tram,

the pd across the motor of the tram,

Discuss the variation in the power output of the motor with distance from the lower station.

Discuss the variation in the power output of the motor with distance from the lower station.

Discuss the variation in the power output of the motor with distance from the lower station.

A cell of negligible internal resistance is connected to three identical resistors. The current in the cell is 3.0 A.

The resistors are now arranged in series.

What is the new current in the cell?

A.  1.0 A

B.  1.5 A

C.  3.0 A

D.  9.0 A

A cell of negligible internal resistance is connected to three identical resistors. The current in the cell is 3.0 A.

The resistors are now arranged in series.

What is the new current in the cell?

A.  1.0 A

B.  1.5 A

C.  3.0 A

D.  9.0 A

Two copper wires of equal lengths but different diameters are used to connect a cell to a load. Wire 1 has a diameter M, wire 2 has a diameter 2M. The electron drift velocities in wires 1 and 2 are $v_1$ and $v_2$.

What is $\frac{v_2}{v_1}$?

A.  $4$

B.  $2$

C.  $\frac{1}{2}$

D.  $\frac{1}{4}$

Two copper wires of equal lengths but different diameters are used to connect a cell to a load. Wire 1 has a diameter M, wire 2 has a diameter 2M. The electron drift velocities in wires 1 and 2 are $v_1$ and $v_2$.

What is $\frac{v_2}{v_1}$?

A.  $4$

B.  $2$

C.  $\frac{1}{2}$

D.  $\frac{1}{4}$

Show that the internal resistance of the cell is about 0.7 Ω.

Show that the internal resistance of the cell is about 0.7 Ω.

Show that the internal resistance of the cell is about 0.7 Ω.

Determine the total power dissipated in the circuit.

Determine the total power dissipated in the circuit.

Determine the total power dissipated in the circuit.

Calculate, in mA, the current in the resistor.

Calculate, in mA, the current in the resistor.

Calculate, in mA, the current in the resistor.

Show that the internal resistance of the cell is about 0.7 Ω.

Show that the internal resistance of the cell is about 0.7 Ω.

Show that the internal resistance of the cell is about 0.7 Ω.

Calculate the emf of the cell.

Calculate the emf of the cell.

Calculate the emf of the cell.

Calculate the maximum current in the chamber due to the electrons when there is no smoke in the chamber.

Calculate the maximum current in the chamber due to the electrons when there is no smoke in the chamber.

Calculate the maximum current in the chamber due to the electrons when there is no smoke in the chamber.

Four identical resistors, each of resistance $R$, are connected as shown.

What is the effective resistance between P and Q?

A.  $\frac{3R}{4}$

B.  $R$

C.  $\frac{4R}{3}$

D.  $4R$

Four identical resistors, each of resistance $R$, are connected as shown.

What is the effective resistance between P and Q?

A.  $\frac{3R}{4}$

B.  $R$

C.  $\frac{4R}{3}$

D.  $4R$

Four identical resistors, each of resistance $R$, are connected as shown.

What is the effective resistance between P and Q?

A.  $\frac{3R}{4}$

B.  $R$

C.  $\frac{4R}{3}$

D.  $4R$

Four identical resistors, each of resistance $R$, are connected as shown.

What is the effective resistance between P and Q?

A.  $\frac{3R}{4}$

B.  $R$

C.  $\frac{4R}{3}$

D.  $4R$

Four identical resistors, each of resistance $R$, are connected as shown.

What is the effective resistance between P and Q?

A.  $\frac{3R}{4}$

B.  $R$

C.  $\frac{4R}{3}$

D.  $4R$

Four identical resistors, each of resistance $R$, are connected as shown.

What is the effective resistance between P and Q?

A.  $\frac{3R}{4}$

B.  $R$

C.  $\frac{4R}{3}$

D.  $4R$

Four identical resistors, each of resistance $R$, are connected as shown.

What is the effective resistance between P and Q?

A.  $\frac{3R}{4}$

B.  $R$

C.  $\frac{4R}{3}$

D.  $4R$

Four identical resistors, each of resistance $R$, are connected as shown.

What is the effective resistance between P and Q?

A.  $\frac{3R}{4}$

B.  $R$

C.  $\frac{4R}{3}$

D.  $4R$

Four identical resistors, each of resistance $R$, are connected as shown.

What is the effective resistance between P and Q?

A.  $\frac{3R}{4}$

B.  $R$

C.  $\frac{4R}{3}$

D.  $4R$

Four identical resistors, each of resistance $R$, are connected as shown.

What is the effective resistance between P and Q?

A.  $\frac{3R}{4}$

B.  $R$

C.  $\frac{4R}{3}$

D.  $4R$

Calculate the maximum current in the chamber due to the electrons when there is no smoke in the chamber.

Calculate the maximum current in the chamber due to the electrons when there is no smoke in the chamber.

Calculate the maximum current in the chamber due to the electrons when there is no smoke in the chamber.

Calculate the maximum current in the chamber due to the electrons when there is no smoke in the chamber.

Calculate the maximum current in the chamber due to the electrons when there is no smoke in the chamber.

In an experiment to determine the resistivity of a material, a student measures the resistance of several wires made from the pure material. The wires have the same length but different diameters.

Which quantities should the student plot on the $x$-axis and the $y$-axis of a graph to obtain a straight line?

In an experiment to determine the resistivity of a material, a student measures the resistance of several wires made from the pure material. The wires have the same length but different diameters.

Which quantities should the student plot on the $x$-axis and the $y$-axis of a graph to obtain a straight line?

What is the relationship between the resistivity $\rho$ of a uniform wire, the radius $r$ of the wire and the length $l$ of the wire when its resistance is constant?

A.  $\rho \propto r^{2}l$

B.  $\rho \propto r{l}^2$

C.  $\rho \propto \frac{l}{r^2}$

D.  $\rho \propto \frac{r^2}{l}$

What is the relationship between the resistivity $\rho$ of a uniform wire, the radius $r$ of the wire and the length $l$ of the wire when its resistance is constant?

A.  $\rho \propto r^{2}l$

B.  $\rho \propto r{l}^2$

C.  $\rho \propto \frac{l}{r^2}$

D.  $\rho \propto \frac{r^2}{l}$

A power station generates $250 \mathrm{kW}$ of power at a potential difference of $25 \mathrm{kV}$. The energy is transmitted through cables of total resistance $4.0 \mathrm{\Omega }$.

What is the power loss in the cables?

A.  $0.04 \mathrm{kW}$

B.  $0.4 \mathrm{kW}$

C.  $4 \mathrm{kW}$

D.  $40 \mathrm{kW}$

A power station generates $250 \mathrm{kW}$ of power at a potential difference of $25 \mathrm{kV}$. The energy is transmitted through cables of total resistance $4.0 \mathrm{\Omega }$.

What is the power loss in the cables?

A.  $0.04 \mathrm{kW}$

B.  $0.4 \mathrm{kW}$

C.  $4 \mathrm{kW}$

D.  $40 \mathrm{kW}$

An electrical power supply has an internal resistance. It supplies a direct current $I$ to an external circuit for a time $t$. What is the electromotive force (emf) of the power supply?

A.  $\frac{\mathrm{total} \mathrm{energy} \mathrm{transferred} \mathrm{to} \mathrm{the} \mathrm{whole} \mathrm{circuit}}{I\times t}$

B.  $\frac{\mathrm{total} \mathrm{power} \mathrm{transferred} \mathrm{to} \mathrm{the} \mathrm{whole} \mathrm{circuit}}{I\times t}$

C.  $\frac{\mathrm{total} \mathrm{energy} \mathrm{transferred} \mathrm{to} \mathrm{the} \mathrm{external} \mathrm{circuit}}{I\times t}$

D.  $\frac{\mathrm{total} \mathrm{power} \mathrm{transferred} \mathrm{to} \mathrm{the} \mathrm{external} \mathrm{circuit}}{I\times t}$

An electrical power supply has an internal resistance. It supplies a direct current $I$ to an external circuit for a time $t$. What is the electromotive force (emf) of the power supply?

A.  $\frac{\mathrm{total} \mathrm{energy} \mathrm{transferred} \mathrm{to} \mathrm{the} \mathrm{whole} \mathrm{circuit}}{I\times t}$

B.  $\frac{\mathrm{total} \mathrm{power} \mathrm{transferred} \mathrm{to} \mathrm{the} \mathrm{whole} \mathrm{circuit}}{I\times t}$

C.  $\frac{\mathrm{total} \mathrm{energy} \mathrm{transferred} \mathrm{to} \mathrm{the} \mathrm{external} \mathrm{circuit}}{I\times t}$

D.  $\frac{\mathrm{total} \mathrm{power} \mathrm{transferred} \mathrm{to} \mathrm{the} \mathrm{external} \mathrm{circuit}}{I\times t}$

An electric motor raises an object of weight $500 \mathrm{N}$ through a vertical distance of $3.0 \mathrm{m}$ in $1.5 \mathrm{s}$. The current in the electric motor is $10 \mathrm{A}$ at a potential difference of $200 \mathrm{V}$. What is the efficiency of the electric motor?

A.  $17 \%$

B.  $38 \%$

C.  $50 \%$

D.  $75 \%$

An electric motor raises an object of weight $500 \mathrm{N}$ through a vertical distance of $3.0 \mathrm{m}$ in $1.5 \mathrm{s}$. The current in the electric motor is $10 \mathrm{A}$ at a potential difference of $200 \mathrm{V}$. What is the efficiency of the electric motor?

A.  $17 \%$

B.  $38 \%$

C.  $50 \%$

D.  $75 \%$

Four resistors of $4 \mathrm{\Omega }$ each are connected as shown.

What is the effective resistance between P and Q?

A.  $1.0 \mathrm{\Omega }$

B.  $2.4 \mathrm{\Omega }$

C.  $3.4 \mathrm{\Omega }$

D.  $4.0 \mathrm{\Omega }$

Four resistors of $4 \mathrm{\Omega }$ each are connected as shown.

What is the effective resistance between P and Q?

A.  $1.0 \mathrm{\Omega }$

B.  $2.4 \mathrm{\Omega }$

C.  $3.4 \mathrm{\Omega }$

D.  $4.0 \mathrm{\Omega }$

Determine the resistance of the variable resistor.

Determine the resistance of the variable resistor.

Determine the resistance of the variable resistor.

Calculate the power dissipated in the circuit.

Calculate the power dissipated in the circuit.

Calculate the power dissipated in the circuit.

State the range of current that the ammeter can measure as the slider S of the potential divider is moved from Q to P.

State the range of current that the ammeter can measure as the slider S of the potential divider is moved from Q to P.

State the range of current that the ammeter can measure as the slider S of the potential divider is moved from Q to P.

Slider S of the potential divider is positioned so that the ammeter reads $20 \text{mA}$. Explain, without further calculation, any difference in the power transferred by the potential divider arrangement over the arrangement in (b).

Slider S of the potential divider is positioned so that the ammeter reads $20 \text{mA}$. Explain, without further calculation, any difference in the power transferred by the potential divider arrangement over the arrangement in (b).

Slider S of the potential divider is positioned so that the ammeter reads $20 \text{mA}$. Explain, without further calculation, any difference in the power transferred by the potential divider arrangement over the arrangement in (b).

Determine the resistance of the variable resistor.

Determine the resistance of the variable resistor.

Determine the resistance of the variable resistor.

Calculate the power dissipated in the circuit.

Calculate the power dissipated in the circuit.

Calculate the power dissipated in the circuit.

State the range of current that the ammeter can measure as the slider S of the potential divider is moved from Q to P.

State the range of current that the ammeter can measure as the slider S of the potential divider is moved from Q to P.

State the range of current that the ammeter can measure as the slider S of the potential divider is moved from Q to P.

Describe, by reference to your answer for (c)(i), the advantage of the potential divider arrangement over the arrangement in (b).

Describe, by reference to your answer for (c)(i), the advantage of the potential divider arrangement over the arrangement in (b).

Describe, by reference to your answer for (c)(i), the advantage of the potential divider arrangement over the arrangement in (b).

A circuit contains a variable resistor of maximum resistance R and a fixed resistor, also of resistance R, connected in series. The emf of the battery is $6.0 \text{V}$ and its internal resistance is negligible.

What are the initial and final voltmeter readings when the variable resistor is increased from an initial resistance of zero to a final resistance of R?

A circuit contains a variable resistor of maximum resistance R and a fixed resistor, also of resistance R, connected in series. The emf of the battery is $6.0 \text{V}$ and its internal resistance is negligible.

What are the initial and final voltmeter readings when the variable resistor is increased from an initial resistance of zero to a final resistance of R?

The diagram shows two cylindrical wires, X and Y. Wire X has a length $l$, a diameter $d$, and a resistivity $\rho$. Wire Y has a length $2l$, a diameter of $\frac{d}{2}$and a resistivity of $\frac{\rho }{2}$.

What is $\frac{\text{resistance of X}}{\text{resistance of Y}}$?

A. 4

B. 2

C. 0.5

D. 0.25

The diagram shows two cylindrical wires, X and Y. Wire X has a length $l$, a diameter $d$, and a resistivity $\rho$. Wire Y has a length $2l$, a diameter of $\frac{d}{2}$and a resistivity of $\frac{\rho }{2}$.

What is $\frac{\text{resistance of X}}{\text{resistance of Y}}$?

A. 4

B. 2

C. 0.5

D. 0.25

Three identical resistors of resistance R are connected as shown to a battery with a potential difference of $12 \text{V}$ and an internal resistance of $\frac{\text{R}}{2}$. A voltmeter is connected across one of the resistors.

What is the reading on the voltmeter?

A. $3 \text{V}$

B. $4 \text{V}$

C. $6 \text{V}$

D. $8 \text{V}$

Three identical resistors of resistance R are connected as shown to a battery with a potential difference of $12 \text{V}$ and an internal resistance of $\frac{\text{R}}{2}$. A voltmeter is connected across one of the resistors.

What is the reading on the voltmeter?

A. $3 \text{V}$

B. $4 \text{V}$

C. $6 \text{V}$

D. $8 \text{V}$

Show that the maximum velocity of the photoelectrons is $700 {\text{km\hspace{0.05em}\hspace{0.05em}s}}^{-1}$.

Show that the maximum velocity of the photoelectrons is $700 {\text{km\hspace{0.05em}\hspace{0.05em}s}}^{-1}$.

Show that the maximum velocity of the photoelectrons is $700 {\text{km\hspace{0.05em}\hspace{0.05em}s}}^{-1}$.

Show that each resistor has a resistance of about 30 Ω.

Show that each resistor has a resistance of about 30 Ω.

Show that each resistor has a resistance of about 30 Ω.

Explain why the output potential difference to the external circuit and the output emf of the photovoltaic cell are different.

Explain why the output potential difference to the external circuit and the output emf of the photovoltaic cell are different.

Explain why the output potential difference to the external circuit and the output emf of the photovoltaic cell are different.

Calculate the internal resistance of the photovoltaic cell for the maximum intensity condition using the model for the cell.

Calculate the internal resistance of the photovoltaic cell for the maximum intensity condition using the model for the cell.

Calculate the internal resistance of the photovoltaic cell for the maximum intensity condition using the model for the cell.

Two wires, $\text{X}$ and $\text{Y}$, are made of the same material and have equal length. The diameter of $\text{X}$ is twice that of $\text{Y}$.

What is $\frac{\text{resistance of X}}{\text{resistance of Y}}$?

A.  $\frac{1}{4}$

B.  $\frac{1}{2}$

C.  $2$

D.  $4$

Two wires, $\text{X}$ and $\text{Y}$, are made of the same material and have equal length. The diameter of $\text{X}$ is twice that of $\text{Y}$.

What is $\frac{\text{resistance of X}}{\text{resistance of Y}}$?

A.  $\frac{1}{4}$

B.  $\frac{1}{2}$

C.  $2$

D.  $4$

The resistance of the loop is 2.4 Ω. Calculate the magnitude of the magnetic force on the loop as it enters the region of magnetic field.

The resistance of the loop is 2.4 Ω. Calculate the magnitude of the magnetic force on the loop as it enters the region of magnetic field.

The resistance of the loop is 2.4 Ω. Calculate the magnitude of the magnetic force on the loop as it enters the region of magnetic field.

Show that the energy dissipated in the loop from t = 0 to t = 3.5 s is 0.13 J.

Show that the energy dissipated in the loop from t = 0 to t = 3.5 s is 0.13 J.

Show that the energy dissipated in the loop from t = 0 to t = 3.5 s is 0.13 J.

The work done to move a particle of charge 0.25 μC from one point in an electric field to another is 4.5 μJ. Calculate the magnitude of the potential difference between the two points.

The work done to move a particle of charge 0.25 μC from one point in an electric field to another is 4.5 μJ. Calculate the magnitude of the potential difference between the two points.

The work done to move a particle of charge 0.25 μC from one point in an electric field to another is 4.5 μJ. Calculate the magnitude of the potential difference between the two points.

In the circuit shown, the battery has an emf of 12 V and negligible internal resistance. Three identical resistors are connected as shown. The resistors each have a resistance of 10 Ω.

The resistor L is removed. What is the change in potential at X?

A.  Increases by 2 V

B.  Decreases by 2 V

C.  Increases by 4 V

D.  Decreases by 4 V

In the circuit shown, the battery has an emf of 12 V and negligible internal resistance. Three identical resistors are connected as shown. The resistors each have a resistance of 10 Ω.

The resistor L is removed. What is the change in potential at X?

A.  Increases by 2 V

B.  Decreases by 2 V

C.  Increases by 4 V

D.  Decreases by 4 V

Two cells are connected in parallel as shown below. Each cell has an emf of 5.0 V and an internal resistance of 2.0 Ω. The lamp has a resistance of 4.0 Ω. The ammeter is ideal.

What is the reading on the ammeter?

A.  1.0 A

B.  1.3 A

C.  2.0 A

D.  2.5 A

Two cells are connected in parallel as shown below. Each cell has an emf of 5.0 V and an internal resistance of 2.0 Ω. The lamp has a resistance of 4.0 Ω. The ammeter is ideal.

What is the reading on the ammeter?

A.  1.0 A

B.  1.3 A

C.  2.0 A

D.  2.5 A

Three identical resistors each of resistance R are connected with a variable resistor X as shown. X is initially set to R. The current in the cell is 0.60 A.

The cell has negligible internal resistance.

X is now set to zero. What is the current in the cell?

A.  0.45 A

B.  0.60 A

C.  0.90 A

D.  1.80 A

Three identical resistors each of resistance R are connected with a variable resistor X as shown. X is initially set to R. The current in the cell is 0.60 A.

The cell has negligible internal resistance.

X is now set to zero. What is the current in the cell?

A.  0.45 A

B.  0.60 A

C.  0.90 A

D.  1.80 A

A circuit consists of a cell of emf E = 3.0 V and four resistors connected as shown. Resistors R₁ and R₄ are 1.0 Ω and resistors R₂ and R₃ are 2.0 Ω.

What is the voltmeter reading?

A.  0.50 V

B.  1.0 V

C.  1.5 V

D.  2.0 V

A circuit consists of a cell of emf E = 3.0 V and four resistors connected as shown. Resistors R₁ and R₄ are 1.0 Ω and resistors R₂ and R₃ are 2.0 Ω.

What is the voltmeter reading?

A.  0.50 V

B.  1.0 V

C.  1.5 V

D.  2.0 V

Three lamps (X, Y and Z) are connected as shown in the circuit. The emf of the cell is 20 V. The internal resistance of the cell is negligible. The power dissipated by X, Y and Z is 10 W, 20 W and 20 W respectively.

What is the voltage across Lamp X and Lamp Y?

Three lamps (X, Y and Z) are connected as shown in the circuit. The emf of the cell is 20 V. The internal resistance of the cell is negligible. The power dissipated by X, Y and Z is 10 W, 20 W and 20 W respectively.

What is the voltage across Lamp X and Lamp Y?

Three lamps (X, Y and Z) are connected as shown in the circuit. The emf of the cell is 20 V. The internal resistance of the cell is negligible. The power dissipated by X, Y and Z is 10 W, 20 W and 20 W respectively.

What is the voltage across Lamp X and Lamp Y?

Three lamps (X, Y and Z) are connected as shown in the circuit. The emf of the cell is 20 V. The internal resistance of the cell is negligible. The power dissipated by X, Y and Z is 10 W, 20 W and 20 W respectively.

What is the voltage across Lamp X and Lamp Y?

Two resistors of equal resistance R are connected with two cells of emf ε and 2ε. Both cells have negligible internal resistance.

What is the current in the resistor labelled X?

A.  $\frac{\epsilon }{2R}$

B.  $\frac{3\epsilon }{2R}$

C.  $\frac{\epsilon }{R}$

D.  $\frac{3\epsilon }{R}$

Two resistors of equal resistance R are connected with two cells of emf ε and 2ε. Both cells have negligible internal resistance.

What is the current in the resistor labelled X?

A.  $\frac{\epsilon }{2R}$

B.  $\frac{3\epsilon }{2R}$

C.  $\frac{\epsilon }{R}$

D.  $\frac{3\epsilon }{R}$

Two resistors of equal resistance R are connected with two cells of emf ε and 2ε. Both cells have negligible internal resistance.

What is the current in the resistor labelled X?

A.  $\frac{\epsilon }{2R}$

B.  $\frac{3\epsilon }{2R}$

C.  $\frac{\epsilon }{R}$

D.  $\frac{3\epsilon }{R}$

Two resistors of equal resistance R are connected with two cells of emf ε and 2ε. Both cells have negligible internal resistance.

What is the current in the resistor labelled X?

A.  $\frac{\epsilon }{2R}$

B.  $\frac{3\epsilon }{2R}$

C.  $\frac{\epsilon }{R}$

D.  $\frac{3\epsilon }{R}$

Two resistors of equal resistance R are connected with two cells of emf ε and 2ε. Both cells have negligible internal resistance.

What is the current in the resistor labelled X?

A.  $\frac{\epsilon }{2R}$

B.  $\frac{3\epsilon }{2R}$

C.  $\frac{\epsilon }{R}$

D.  $\frac{3\epsilon }{R}$

Two resistors of equal resistance R are connected with two cells of emf ε and 2ε. Both cells have negligible internal resistance.

What is the current in the resistor labelled X?

A.  $\frac{\epsilon }{2R}$

B.  $\frac{3\epsilon }{2R}$

C.  $\frac{\epsilon }{R}$

D.  $\frac{3\epsilon }{R}$

Two resistors of equal resistance R are connected with two cells of emf ε and 2ε. Both cells have negligible internal resistance.

What is the current in the resistor labelled X?

A.  $\frac{\epsilon }{2R}$

B.  $\frac{3\epsilon }{2R}$

C.  $\frac{\epsilon }{R}$

D.  $\frac{3\epsilon }{R}$

Two resistors of equal resistance R are connected with two cells of emf ε and 2ε. Both cells have negligible internal resistance.

What is the current in the resistor labelled X?

A.  $\frac{\epsilon }{2R}$

B.  $\frac{3\epsilon }{2R}$

C.  $\frac{\epsilon }{R}$

D.  $\frac{3\epsilon }{R}$

X and Y are two conductors with the same diameter, made from the same material. Y is twice the length of X. They are connected in series to a cell of emf ε.

X dissipates power P.

What is the power dissipated by Y?

A.  $\frac{P}{2}$

B.  P

C.  2P

D.  4P

X and Y are two conductors with the same diameter, made from the same material. Y is twice the length of X. They are connected in series to a cell of emf ε.

X dissipates power P.

What is the power dissipated by Y?

A.  $\frac{P}{2}$

B.  P

C.  2P

D.  4P

X and Y are two conductors with the same diameter, made from the same material. Y is twice the length of X. They are connected in series to a cell of emf ε.

X dissipates power P.

What is the power dissipated by Y?

A.  $\frac{P}{2}$

B.  P

C.  2P

D.  4P

X and Y are two conductors with the same diameter, made from the same material. Y is twice the length of X. They are connected in series to a cell of emf ε.

X dissipates power P.

What is the power dissipated by Y?

A.  $\frac{P}{2}$

B.  P

C.  2P

D.  4P

Four identical lamps are connected in a circuit. The current through lamp L is I.

The lamps are rearranged using the same cell.

What is the current through L?

A.  $\frac{I}{4}$

B.  $\frac{I}{2}$

C.  I

D.  2I

Four identical lamps are connected in a circuit. The current through lamp L is I.

The lamps are rearranged using the same cell.

What is the current through L?

A.  $\frac{I}{4}$

B.  $\frac{I}{2}$

C.  I

D.  2I

Four identical lamps are connected in a circuit. The current through lamp L is I.

The lamps are rearranged using the same cell.

What is the current through L?

A.  $\frac{I}{4}$

B.  $\frac{I}{2}$

C.  I

D.  2I

Four identical lamps are connected in a circuit. The current through lamp L is I.

The lamps are rearranged using the same cell.

What is the current through L?

A.  $\frac{I}{4}$

B.  $\frac{I}{2}$

C.  I

D.  2I

A variable resistor is connected to a cell with emf ε and internal resistance r as shown. When the current in the circuit is I, the potential difference measured across the terminals of the cell is V.

The resistance of the variable resistor is doubled.

What is true about the current and the potential difference?

A variable resistor is connected to a cell with emf ε and internal resistance r as shown. When the current in the circuit is I, the potential difference measured across the terminals of the cell is V.

The resistance of the variable resistor is doubled.

What is true about the current and the potential difference?

A variable resistor is connected to a cell with emf ε and internal resistance r as shown. When the current in the circuit is I, the potential difference measured across the terminals of the cell is V.

The resistance of the variable resistor is doubled.

What is true about the current and the potential difference?

A variable resistor is connected to a cell with emf ε and internal resistance r as shown. When the current in the circuit is I, the potential difference measured across the terminals of the cell is V.

The resistance of the variable resistor is doubled.

What is true about the current and the potential difference?

Show that the current in Q is 0.45 A.

Show that the current in Q is 0.45 A.

Show that the current in Q is 0.45 A.

Show that the current in Q is 0.45 A.

Show that the current in Q is 0.45 A.

Show that the current in Q is 0.45 A.

Calculate the resistance of R.

Calculate the resistance of R.

Calculate the resistance of R.

Calculate the resistance of R.

Calculate the resistance of R.

Calculate the resistance of R.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

The designers state that the energy transferred by the resistor every second is 15 J.

Calculate the current in the resistor.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.

The resistor has a cross-sectional area of 9.6 × 10⁻⁶ m².

Show that a resistor made from carbon fibre will be suitable for the pad.