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WorksheetsP7 - Electromagnetic effects - Revision
Total questions: 31
Worksheet time: 25mins
An e.m.f. is induced across a wire when it moves through the magnetic field between the poles of a magnet. Which electrical device operates because of this effect?
a battery
a cathode-ray tube
a generator
a motor
The process of creating a current in a circuit by changing a magnetic field
electric generator
electric motor
electromagnetic induction
magnet
The diagram shows a transformer.
The input voltage is 240 V.
What is the output voltage?
6.0 V
12 V
20 V
40 V
A transformer has 50 turns on its primary coil and 100 turns on its secondary coil. An alternating
voltage of 25.0 V is connected across the primary coil.
What is the voltage across the secondary coil?
12.5 V
50.0 V
100 V
200 V
What is an advantage of transmitting electricity at a high voltage?
It is faster.
It is safer.
Less energy is wasted.
Less equipment is needed.
An e.m.f. is induced across a wire when it moves through the magnetic field between the poles of
a magnet.
Which electrical device operates because of this effect?
a battery
a cathode-ray tube
a generator
a motor
A current-carrying coil in a magnetic field experiences a turning effect.
How can the turning effect be increased?
Reduce the size of the current.
Increase the number of turns on the coil.
Use thinner wire for the coil.
Reverse the direction of the magnetic field.
Which device uses slip rings?
a d.c. electric motor
a relay
a transformer
an a.c. generator
What are split ring commutators needed for?
Decreasing the current every half turn
Increasing the current every half turn
Reversing the current every half turn
Stopping the current every half turn
D.C. motors convert ________ energy into _________ energy.
Complete the sentence.
Chemical, Mechanical
Electrical, Mechanical
Mechanical, Kinetic
Kinetic, Mechanical
Using the right hand rule, B represents the direction of the
current
magnetic field
Calculate potential difference in the secondary coil based on the information given below.
Vp = 240 V
Np = 20
Ns = 125
Vs ?
1500
500
1000
2000
What is the material used for construction of transformer core?
Aluminium
Copper
Iron
Wood
In the sketch above, a conductor carrying conventional current, I, is placed in a magnetic field. Which ONE of the following best describes the direction of the magnetic force experienced by the conductor?
Parallel to the direction of the magnetic field
Opposite to the direction of the magnetic field
Into the page perpendicular to the direction of the magnetic field
Out of the page perpendicular to the direction of the magnetic field
The function of a transformer is to ...
raise and lower the apparent power levels
transfer DC voltage from the primary winding to the secondary winding
increase or decrease A.C voltage or A.C current levels
transform mechanical energy into electrical energy
Assume primary has 240 turns and secondary has 60 turns. Primary is connected with 120V AC power supply. What is the voltage on the secondary?
30 V
0.333 V
2 V
120V
What quantities are changed in a step-up transformer?
Voltage increases
Voltage decreases
Current increases
Current decreases
Which images shows the voltage trace for a.c?
What is the function of the motor?
Convert electrical energy to mechanical (kinetic) energy
Convert electrical energy to thermal energy (heat)
Convert mechanical (kinetic) energy to electrical energy
What is the function of the generator?
Convert electrical energy to mechanical (kinetic) energy
Convert electrical energy to thermal energy (heat)
Convert mechanical (kinetic) energy to electrical energy
What type of transformer is a location B?
step up
step down
What type of transformer is A?
Step up
Step down
Which best describes how a motor works?
When a fan blows on a wire, it causes it to spin, creating a force.
When a fan blows on a wire, it causes it to spin, creating an electrical current.
When a wire that carries electrical current is placed in zero gravity, the wire experiences a force.
When a wire that carries electrical current is placed in a magnetic field, the wire experiences a force.
What does the direction of the magnetic field depend on?
The direction of the magnetic field will depend on the direction of the current flow
The direction of the magnetic field will depend on the direction of the magnetic domains
A
B
C
D
A
B
C
D
A
B
C
D
