11 mark
Four students, of varying ability in physics, draw what they believe to be the field pattern of a current-carrying solenoid.
Which of them is correct?
Did this page help you?
4.4 Electromagnetic Effects
21 mark
Four students are asked to draw the magnetic field pattern of a current-carrying wire. The wire is carrying the current out of the page.
The diagrams they draw are shown below.
Which is correct?
Did this page help you?
31 mark
Which device uses a split ring commutator?
A DC motor
A transformer
A relay
An AC generator
Did this page help you?
41 mark
A simple DC electric motor is shown in the diagram.
Which of the following changes would make the coil turn more quickly?
Reducing the strength of the magnetic field.
Reversing the direction of the current AND swapping the magnetic poles.
Swapping the magnetic poles.
Increasing the current in the coil
Did this page help you?
51 mark
The number of turns in the primary coil and secondary coil of a transformer is Np and Ns respectively.
Which of the following statements represents a step-up transformer?
Np = Ns
Np < Ns
Ns < Np
Np > Ns
Did this page help you?
11 mark
Transformers are used to change the voltage of a power supply.
The diagram below shows a simple transformer.
If the input voltage is 48V, what is the output voltage?
667V
2.4V
9.6V
240V
Did this page help you?
21 mark
A magnetic field can be represented by the diagram shown below. The dots represent magnetic field lines coming out of the page:
A beam of alpha particles is directed through the field as shown above. Alpha particles, being charged, will be deflected by the field. In which direction will they be deflected?
Upwards
Downwards
Into the page
Out of the page
Did this page help you?
31 mark
The South pole of a magnet is brought near to a solenoid, which is connected to an ammeter. The magnet is then pulled away again.
As the magnet is moved towards and then away from point P, the needle on the ammeter deflects.
What magnetic pole is produced at P when the south pole of the magnet is brought towards and away from the solenoid?
|
S pole brought towards P |
S pole moved away from P |
|
|
A |
N |
N |
|
B |
N |
S |
|
C |
S |
N |
|
D |
S |
S |
Did this page help you?
41 mark
A current-carrying wire is placed between two magnetic poles as shown in the diagram below. It experiences an upwards force.
What is the orientation of the magnetic poles?
|
Left magnet |
Right magnet |
|
|
A |
N |
N |
|
B |
S |
N |
|
C |
N |
S |
|
D |
S |
S |
Did this page help you?
51 mark
A transformer is used to raise the voltage of electricity which is produced at a power station for transmission in power lines.
The power station produces 100 MW of power. The transformer steps this up to a voltage of 400 kV for transmission in power lines.
Assume that the transformer is 100% efficient.
What current flows in the power lines?
250 A
0.25 A
4 x 1013 A
40,000 A
Did this page help you?
61 mark
A transformer has 1200 turns on its secondary coil, and outputs 240 V.
If the input voltage is 12 V, how many turns are there on the primary coil?
2.4
24,000
60
1200
Did this page help you?
71 mark
A current-carrying wire is placed into a magnetic field as shown in the diagram. The wire experiences a force.
In which direction is the force?
OP
PO
ST
QR
Did this page help you?
11 mark
Which of the following methods could be used to demagnetise a permanent magnet?
Cool it to a very low temperature.
Put it in a coil of wire and pass direct current through the wire.
Stroke it in a single direction with a permanent magnet.
Heat it to a high temperature
Did this page help you?
21 mark
After being produced at a power station, electrical voltage is increased significantly for transportation across the country via the national grid.
What is the advantage of transmitting electricity at very high voltages?
It makes the electricity flow more quickly.
It increases the efficiency of the electricity transfer.
It produces more power.
It is safer to transmit electricity at high voltage.
Did this page help you?
31 mark
When a wire is moved through a magnetic field, an e.m.f. is induced in that wire.
This rather remarkable effect allows which device to operate?
An electric motor
An electrical generator
A photon accelerator
A transformer.
Did this page help you?
41 mark
Beta and gamma radiation are passed through two metal plates, with equal and opposite charges, as shown in the diagram below.
Which direction, if any, would the β-particles and γ-rays be deflected?
| β-particles | γ-rays | |
| A | into the page | continue straight |
| B | towards the negative plate | out of the page |
| C | continue straight | towards the negative plate |
| D | towards the positive plate | continue straight |
Did this page help you?
51 mark
One of the diagrams below represents the output of a simple A.C. generator.
Which one is correct?
Did this page help you?