GCSE Magnetism quiz - by J Catchpole

Magnetic fields

1.) The definition of a magnetic field is: "A magnetic field is a region where magnetic materials and also wires carrying currents, experience a force acting on them". Which of the following materials are magnetic?

Iron, Nickel, Cobalt, and their alloys.

Iron, Nickel, Steel, and Aluminium.

Tin, Steel, and Aluminium.

Tin, Cobalt, and their alloys.

2.) Study the diagrams carefully. Which one correctly shows the magnetic field lines of a bar magnet?

A.

B.

C.

D.

3.) A solenoid is a coil of current carrying wire with its length larger in comparison with its diameter. When a current passes in a solenoid, what can be said about the magnetic field pattern around and inside it?

It is uniform.

It is made up of straight lines.

Outside it is similar to the field around a bar magnet and is uniform on the inside.

Outside it consists of a series of concentric circles and is made up of straight lines on the inside.

4.) Study the diagram carefully. Which of the following have to be brought together to produce the magnetic field pattern shown?

North pole and South pole.

South pole and a piece of unmagnetised iron.

North pole and North pole.

South pole and North pole.

5.) Study the diagram carefully. Which of the following have to be brought together to produce the magnetic field pattern shown?

North pole and South pole.

South pole and a piece of aluminium.

North pole and North pole.

South pole and South pole.

6.) The Earth has its own magnetic field. If a compass needle points towards the Northern Hemisphere, what pole is it pointing to?

Magnetic South pole.

Magnetic North pole.

Geographic South pole.

Geographic North pole.

7.) Study the diagrams carefully. They show a compass resting on a piece of card. Passing through a hole in the card is a wire, which has a large current flowing through it. From the direction in which you are looking, which way will the compass needle point if the current flows into the screen?

A.

B.

C.

D.

8.) An unmagnetised bar of steel is tested at both ends by the north pole of a permanent magnet. Which of the following is observed?

Attraction to both ends.

Attraction at one end only.

Repulsion from one end only.

Repulsion from both ends.

9.) A piece of metal is labelled XY. When the north pole of a magnet is held near to end X, the metal is attracted. The same happens when the north pole is held near to Y. What is the piece of metal XY most likely to be?

A piece of unmagnetised iron.

A piece of aluminium.

A piece of electrically charged metal.

A magnet.

Electromagnets

10.) The strength of an electromagnet depends on three factors. Which of the following is least likely to effect the strength of an electromagnet?

The size of the current.

The number of turns the coil has.

The type of material the core is made of.

The type of wire the coil is made of.

11.) A coil of wire is wound around a metal core to form an electromagnet. Which of these arrangements of electromagnets will lift the greatest mass of iron when a current of 2 amps flows through it?

40 turns of wire, and a Copper core.

200 turns of wire, and a Soft Iron core.

30 turns of wire, and a Steel core.

200 turns of wire, and an Aluminium core.

12.) Two electromagnets are labelled "A" and "B". When looking at electromagnet "A" end on, the current flows clockwise. When looking at electromagnet "B" end on, the current flows anticlockwise. Which poles are being observed on each electromagnet respectively?

"A" - North pole, "B" - South pole.

"A" - South pole, "B" - North pole.

"A" and "B" - North pole.

"A" and "B" - South pole.

13.) Which of the following statements is NOT true about magnetic materials?

Magnetically "Soft" means that it changes easily between being magnetised and demagnetised. "Hard" means that it will retain its magnetism.

Steel is magnetically "Hard" making it ideal for permanent magnets.

Iron is magnetically "Soft" making it ideal for electromagnets.

Aluminium is magnetically "Soft" making it ideal for electromagnets.

14.) To magnetise a piece of steel you put it into a solenoid with a steady DC supply, turn off the current and take it out. How do you demagnetise a piece of steel?

Put it into a solenoid with a DC supply and then pull it out with the current still on.

Put it into a solenoid with an AC supply and then pull it out with the current still on.

Put it into a solenoid with an AC supply and then pull it out with the current off.

Put it into a solenoid with a DC supply and then pull it out with the current off.

Electromagnetic Devices

15.) Electromagnetic devices have a magnetically soft core. Why is this?

To make the device harder to magnetise.

To decrease the strength of the magnet.

So that when the current is turned off, the magnetism stays.

So that when the current is turned off, the magnetism disappears.

16.) If used drinks containers are to be recycled, they need to be sorted. One way of doing this is to separate those that are magnetic from those that are not. From a selection of steel, tin and aluminium cans, which ones will stick to a magnet?

Both the Aluminium and the Tin cans.

Both the Steel and the Tin cans.

Only the Aluminium cans.

Only the Steel cans.

17.) Which of the following devices does NOT have an electromagnet in it?

A circuit breaker.

A loudspeaker.

A fuse.

An electric bell.

18.) What does a circuit breaker do when the current flowing in its circuit, becomes too high?

Reduces the current flowing, to a safer level.

Breaks the device in the circuit so it can not be used again.

"Trips", breaking the circuit and protects the device in the circuit.

"Trips", breaking the circuit and renders the circuit breaker useless.

19.) What is a relay used for?

To relay the power around a circuit breaker that has tripped.

To relay the power around a fault in a circuit.

To turn on/off a high current circuit from a low current circuit.

To turn on/off a low current circuit from a high current circuit.

20.) In an electric bell, how does the electromagnet continuously turn on and off, to make the bell ring?

The person ringing the bell turns the electromagnet on and off rapidly by a switch to make it ring.

The circuit contains a circuit breaker, which continuously breaks the circuit.

The iron arm, which hits the bell, is part of the circuit and so continuously breaks and completes the circuit.

The current is AC and so continuously attracts and repels the iron arm, thus turning on and off the electromagnet.

The Motor Effect

21.) A wire carrying an electrical current is placed between two bar magnets. In this situation the wire experiences a force. How might the size of this force be increased?

Increase the current through the wire.

Increase the separation between the magnetic poles.

Decrease the strength of the magnetic field.

Reverse the poles of the magnets.

22.) A current in a magnetic field experiences a force. Which of the following statements is NOT true?

The force is at right angles to both the wire and the magnetic field.

The greatest force is experienced when the wire is at right angles to the magnetic field.

If the wire is parallel to the magnetic field, then no force will be experienced.

The Right Hand Thumb Rule can be used to predict which way the force will act.

23.) When using Fleming's Left Hand Rule, the Thumb shows the direction of what?

The Electrons.

The Force or Motion.

The Field.

The Current.

24.) Increasing the current to an electric motor will speed its rotation up. Which of the following will NOT speed it up?

Using a low resistance wire in the coil.

Using an AC supply.

Using a stronger magnetic field.

Using more turns on the coil.

25.) What is used to swap the contacts on an electric motor every half turn to keep it rotating in the same direction?

A DC supply.

An AC supply.

A Split Ring Commutator.

Slip Rings.

26.) Loudspeakers demonstrate the Motor effect. Which of the following statements is NOT true?

DC signals from the amplifier are fed to the speaker coil.

The signals make the coil move back and forth over the north pole of the magnet.

The paper cone is attached to the coil and so this also moves back and forth.

These vibrations from the paper cause the air to vibrate, which creates the sound that we hear.

Electromagnetic Induction

27.) The movement of a wire in and out of a magnetic field will produce a current in the wire. This effect is called electromagnetic induction. Which of the following will also cause electromagnetic induction?

A constant force.

A changing force.

A constant magnetic field.

A changing magnetic field.

28.) A circuit consists of a galvanometer connected to a conductor. The galvanometer is an instrument that can measure electric current. What will be observed about the needle of the galvanometer when the conductor is moved into a magnetic field in one direction and then left there?

It will deflect in one direction and then return to zero.

It will deflect in one direction and remain deflected.

It will oscillate around zero.

It will remain stationary.

29.) There are three factors which will increase the size of an induced current. Which one of these is NOT one of them?

Increase the strength of the magnet.

Increase the speed of movement of either the conductor or the magnet.

Increase the number of turns on the coil.

Increase the distance between turns on the coil.

30.) Which of the following statements is NOT true about generators?

They are similar to a motor.

They have slip ring commutators instead of a split ring commutator.

They produce steady DC.

Faster revolutions produce a higher overall voltage.

31.) Which of the following statements is NOT true about dynamos?

They are slightly different to generators because the magnet rotates instead of the coil.

A rotating magnet means the field through the coil does not swap every half turn.

They produce AC.

Faster revolutions produce a higher overall voltage.

Transformers

32.) What does a Step-down transformer do?

Increases an alternating voltage.

Decreases an alternating voltage.

Increases a direct voltage.

Decreases a direct voltage.

33.) Transformers have a laminated iron core with layers of insulation. This is done to reduce magnetic eddy currents which heat the iron core, wasting energy. Which of the following statements is NOT true about transformers?

Transformers will only work with AC because they require a changing magnetic field.

No electricity flows around the iron core.

Step-up transformers increase the voltage.

Step-up transformers have more turns on the primary coil.

34.) Study the formulae carefully. Which one is the correct formula for a transformer?

A.

B.

C.

D.

35.) Study the formulae carefully. Which one is correct, showing that transformers can be imagined as being 100% efficient?

A.

B.

C.

D.

36.) A transformer has 1000 turns on the primary coil and 500 turns on the secondary coil. The output voltage is 12V, what must the input voltage be?

6V.

12V.

24V.

240V.

37.) A transformer works from a 240V main's supply. If there are 200 turns on the primary coil and the output voltage is 24V, how many turns must there be on the secondary?

2

20

200

2000

38.) A transformer is used to produce a voltage of 6V for an 18W bulb. If the output arm of the transformer has 30 turns, which of the inputs listed below would allow the lamp to glow at normal brightness?

20V DC and 100 Turns.

100V DC and 20 Turns.

20V AC and 100 Turns.

100V AC and 20 Turns.

39.) A transformer has an input voltage of 12V and an input current of 1.5A. Its output voltage is 24V. What is its output current?

0.75A.

3A.

192A.

432A.

40.) A transformer has an input current of 22A. Its output voltage is 110V and its output current is 1.5A. What is its input voltage?

7.5mV.

75mV.

7.5V.

75V.

41.) A transformer works from a 25,000V supply. If there are 10,000 turns on the secondary coil and the output voltage is 400,000V, how many turns must there be on the primary?

625.

6250.

16000.

160000.

42.) Imagine a magnetic field that crosses the screen from right to left and a wire in this field, which has a current that flows from the bottom to the top of the screen. Use Fleming's Left Hand Rule to predict the direction of the force on the wire. What direction is this force?

Towards the bottom of the screen.

Towards the right of the screen.

Out of the screen.

Into the screen.

43.) A transformer has an input voltage of 240V and an input current of 2A. Its output current is 10mA (0.01A). What is its output voltage?

48V.

480V.

4,800V.

48,000V.

44.) A transformer has 600 turns on the primary coil and 200 turns on the secondary coil. The input voltage is 720V, what must the output voltage be?

240V.

2400V.

216V.

2160V.

45.) A transformer has an input voltage of 3V. Its output voltage is 240V and its output current is 0.25mA. What is its input current?

0.02mA.

0.02A.

0.2A.

20A.

Mixed Bag

46.) A circuit consists of a galvanometer connected to a coil. The galvanometer is an instrument that can measure electric current. What will be observed about the needle of the galvanometer when a magnet is moved in and out of the coil?

It will deflect in one direction and then return to zero.

It will deflect in one direction and remain deflected.

It will oscillate around zero.

It will remain stationary.

47.) A transformer is used to produce a voltage of 240V for a 180W bulb. If the input arm of the transformer has 30 turns, which of the combinations listed below would allow the lamp to glow at normal brightness?

12V DC Input and 600 Turns on the Output arm.

24V DC Input and 1200 Turns on the Output arm.

12V AC Input and 600 Turns on the Output arm.

24V AC Input and 1200 Turns on the Output arm.

48.) Study the diagram carefully. From the "Split Ring Commutator" end of the motor, which way does the coil move?

It does not move.

It oscillates up and down.

It rotates clockwise.

It rotates anticlockwise.

49.) When using Fleming's Left Hand Rule, the Second Finger shows the direction of what?

The Electrons.

The Force.

The Field.

The Current.

50.) When using Fleming's Left Hand Rule, the First Finger shows the direction of what?

The Electrons.

The Force.

The Field.

The Current.