AQA A-level electricity questions

The two resistors shown are both uniform cylinders of equal length made from the same conducting putty.

The diameter of Y is twice that of X. The resistance of Y is R.

What is the total resistance of the combination?

• $\frac{4R}{5}$

• 3R

• 4R

• 5R

A voltmeter is used to measure potential difference for a component X.

Which row gives the position and ideal resistance for the voltmeter?

• A

• B

• C

• D

The combined resistance of n identical resistors connected in parallel is R_n.

Which statement correctly describes the variation of R_n as n increases?

• R_n decreases linearly as n increases

• R_n decreases non-linearly as n increases

• R_n increases linearly as n increases

• Rn increases non-linearly as n increases

In the circuit below, the potential difference across the light emitting diode (LED) is 1.8 V when it is emitting light.The current in the circuit is 20 mA.

What is the value of the resistor R?

• 80 Ω

• 90 Ω

• 150 Ω

• 180 Ω

The table shows the resistivity, length and cross-sectional area of wires P and Q.

The resistance of wire P is R.

What is the total resistance of the wires when they are connected in parallel?

• $\frac{R}{9}$

• $\frac{R}{3}$

• $\frac{2R}{3}$

• $\frac{3R}{2}$

he figure shows a light dependent resistor (LDR) and fixed resistor R connected in series across a cell. The internal resistance of the cell is negligible.

Which row shows how the readings on the ammeter and the voltmeter change when the light intensity incident on the LDR is increased?

• A

• B

• C

• D

A wire has a resistance R.

What is the resistance when both the length and radius of the wire are doubled

• $\frac{R}{4}$

• $\frac{R}{2}$

• 2R

• 4R

The current in the cell is 10 A as shown.

What is the current in the 2.0 Ω resistor?

• 0.35A

• 2.86A

• 3.50A

• 7.14A

Which graph shows the variation of the resistance with temperature for an ntc thermistor?

• A

• B

• C

• D

Which statement about superconductors is correct?

• When a material becomes a superconductor, its resistivity is almost zero.

• The temperature at which a material becomes a superconductor is called the critical temperature.

• When

  current passes through a superconductor the pd across it becomes a maximum.

• Copper is a superconductor at room temperature