Drill (Electrical Quantities)

A wire has a certain electrical resistance.

The diameter and length of the wire may be changed.

Which pair of changes must cause the resistance of the wire to increase?

• A

• B

• C

• D

The diagram shows a battery connected to two resistors.

Four students separately measure the electromotive force (e.m.f.) of the battery, the current in the resistors, and the potential difference (p.d.) across resistor R.

Their results are shown in the table below. Which row shows values with their correct units?

• emf= 3.0 A

  current= 0.30 V

  p.d.=1.5A

• emf= 3.0 A

  current= 0.30 A

  p.d.=1.5V

• emf= 3.0 V

  current= 0.30 V

  p.d.=1.5A

• emf= 3.0 V

  current= 0.30 A

  p.d.=1.5V

A resistor converts 350J of electrical energy to other forms of energy. What is the amount of charge that flows through it when a p.d. of 7V is applied across it?

• 0.20 C

• 50 C

• 350 C

• 2450 C

A charge of 4.00 x 10^4 C flows through an electric heater. If the amount of electrical energy converted into thermal energy is 9.00 MJ, calculate the potential difference across the ends of the heater.

• 330 V

• 325 V

• 225 V

• 210 V

The diagram shows a piece of metal resistance wire. Which wire, made of the same metal, has a smaller resistance?

• a wire of greater length with the same diameter

• a wire of the same length with a smaller diameter

• a wire of greater length with the same diameter

• a wire of the same length with a larger diameter

A student wishes to measure first the electromotive force (e.m.f.) of a battery, and then the potential difference (p.d.) across a resistor.

She has the resistor, the battery and some connecting wires. What else does she need?

• a voltmeter only

• an ammeter only

• an ammeter and a voltmeter

• a force meter (newton meter) and a voltmeter

A small heater has a rating of 15 V, 4 A. How much energy does it consume if it is turned on for two minutes?

• 7.5 J

• 120 J

• 450 J

• 7200 J

A 30 Ω resistor is connected in series with another resistor and a 6.0V battery. The current in the circuit is 0.12 A. A voltmeter is connected across the other resistor. What is the reading on the voltmeter?

• 6.0V

• 9.6V

• 2.4V

• 3.6V

A small potential difference V is applied across a filament lamp. The current I in the lamp is measured. V is increased in stages and I is measured at each stage.

Which graph shows the results obtained?

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• 
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In the circuit shown, the ammeter reads 2.0 A and the voltmeter reads 12 V. How much energy is transferred by the resistor in 10 seconds?

• 1440J

• 240J

• 14.4J

• 2.4J