Capacitors - A-level questions

With respect to the capacitor, which relationship is true?

• C = Q/V
• V = C×Q
• Q = C/V
• Q = V/C

What is the voltage across   the plates of the capacitor if  the capacitance is 10 uF and the Charge stored is  30 uC?

• 0.333 V
• 3 V
• 300 V

If 4μF and 2μF capacitors are conneced in series, the equivalent capacitor is ___________.

• 1.33μF

• 0.75μF

• 6μF

• 2μF

If capacitors are connected in parallel, then potential difference across each capacitor is

• same

• zero

• different

• infinite

When a 4 V battery is connected to a capacitor, what is the voltage across the capacitor after a long period of time?

• 0.0 V

• 2.0 V

• 4.0 V

• 3.0 V

In the capacitor, greater plate area gives: 

• greater capacitance
• less capacitance
• no change

A student designs a circuit with a time constant of 5.0 s. State the value of the resistance of the circuit if the capacitor is a 1 mF.

• 5.0 ohms

• 50 ohms

• 500 ohms

• 5000 ohms

Select the best definition of the time constant.

• τ = RC

• The time taken for the p.d to decrease to 1/e of its initial value.

• the time taken for the current to increase to 67% of its initial value.

• time time taken for the p.d to decrease to 0 V.

Fig. 20.2 shows an arrangement of capacitors connected to a battery.

The e.m.f. of the battery is 12 V.

Calculate the total energy E stored by the capacitors in this circuit.

E = .................................... J (Answer to 2 sig fig and don't add units)

Fig. 4.1 shows a circuit with a capacitor of capacitance 0.010 F.

A tight bundle of wire is made from 5.0 m of insulated wire of diameter 0.12 mm and resistivity 4.9 × 10^–7 Ω m. The material of the wire has density 8900 kg m^–3 and specific heat capacity 420 J kg^–1 K^–1.

Calculate the time constant of the circuit. (2 sig fig and unit symbol needed)