Electricity and Magnetism

A polythene rod is rubbed with a cloth and the cloth becomes positively charged.

Which statement describes the transfer of charge?

• Negative charges are transferred from the cloth to the polythene.

• Negative charges are transferred from the polythene to the cloth.

• Positive charges are transferred from the cloth to the polythene.

• Positive charges are transferred from the polythene to the cloth.

A charge of 45 C flows through an electric appliance in 3.0 minutes.

What is the average current in the appliance?

• 0.25 A

• 4.0 A

• 15 A

• 135 A

How can one volt also be expressed?

• one coulomb per ampere

• one coulomb per joule

• one joule per ampere

• one joule per coulomb

The diagram shows a battery of three 1.5 V cells. What is an advantage of this arrangement of cells?

• The battery can supply a current for a longer time than a single 1.5 V cell.

• The battery can supply any e.m.f. between 0 V and 4.5 V.

• The battery supplies more energy to each coulomb of charge than a single 1.5 V cell.

• The e.m.f. of the battery is 4.5 V.

Which diagram shows the arrangement of the ammeter and voltmeter to obtain readings to find

the power of a lamp?

• A

• B

• C

• D

A 6.0 V battery is connected to a network containing five identical resistors. A voltmeter has one lead connected to point K as shown.

At which point should lead L be connected so that the voltmeter reads 3.0 V?

• A

• B

• C

• D

The diagram shows the wiring of a three-pin mains plug. There is an error in the diagram. What is the error?

• The cable cover C is not under the clip S.

• The earth wire E is connected to the wrong terminal.

• The fuse F is connected to the live wire L.

• The live wire L is connected to the wrong end of the fuse F.

A 100 W lamp is switched on for five hours each day for three weeks. The cost of one unit of electricity is $ 0.24. How much does it cost to run the lamp for this time?

• $ 0.36

• $ 0.84

• $ 2.52

• $ 25.20

The diagram shows a simple d.c. motor. The switch is closed and the coil rotates. Which change makes the coil rotate in the opposite direction and at a faster rate?

• increase the current in the coil and increase the number of turns in the coil

• reverse both the magnetic field and the current in the coil

• reverse the magnetic field and decrease the current in the coil

• reverse the magnetic field and increase the current in the coil

The diagram shows a wire PQ between the N-pole and the S-pole of a magnet. There is a current in the wire in the direction of the arrow. What is the direction of the force on the wire PQ?

• into the page

• out of the page

• towards the N-pole

• towards the S-pole