HS11A Revision Questions

Which charge can be carried by a charge carrier?

• 1.1 x 10^-19 C

• 4.0 x 10^-19 C

• 4.8 x 10^-19 C

• 9.1 x 10^-19 C

A resistor of resistance R is connected across a cell of electromotive force (e.m.f.) E and negligible internal resistance.

Which single change to the circuit would lead to the largest increase in the power dissipated in the resistor?

• doubling the value of E

• doubling the value of R

• halving the value of E

• halving the value of R

An electrical cable is made up of one thick strand of copper wire that is surrounded by eight thin strands of copper wire. All nine strands of wire are connected in parallel with each other. A cross-section of the cable is shown.

Each thin strand of wire has cross-sectional area A and length L. The thick strand of wire has cross-sectional area 4A and length L. The cable has total resistance R. Which expression gives the resistivity of copper?

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A car has sensors for detecting the light intensity and temperature of its environment. The sensors make use of a light-dependent resistor (LDR) and a thermistor. The car moves from a warm and dark environment into a cold and bright environment.

What are the changes to the resistances of the LDR and thermistor?

• A

• B

• C

• D

Kirchhoff’s first law is a consequence of the conservation of which quantity?

• charge

• energy

• momentum

• potential difference

In the potentiometer circuit shown, the reading on the ammeter is zero.

The light-dependent resistor (LDR) is then covered and the ammeter gives a non-zero reading. Which change could return the ammeter reading to zero?

• decreasing the supply voltage

• increasing the supply voltage

• moving the sliding contact to the left

• moving the sliding contact to the right

The electric current in a metal wire is 4.0 mA.

How many electrons pass a fixed point in the wire in a time of 10 hours?

• 2.5 x 10¹⁷

• 2.5 x 10²⁰

• 9.0 x 10²⁰

• 9.0 x 10²³

What is the definition of the potential difference across an electrical component?

• the charge per unit time passing through the component

• the energy transferred per unit charge

• the force per unit charge

• the resistance per unit current

Which graph shows the I–V characteristic of a filament lamp?

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A metal wire has a length of 2.50 m and a cross-sectional area of 4.50 x 10^-6 m² . The resistivity of the metal is 3.50 x 10^-7 Ωm.

The wire is stretched so that its length increases to 2.65 m. The wire remains cylindrical and the volume of the wire remains constant.

What is the change in the resistance of the wire?

• 0.012 Ω

• 0.024 Ω

• 0.19 Ω

• 0.22 Ω