WorksheetsDC Motor and Transformers
Total questions: 20
Worksheet time: 11mins
A
B
C
D
A
B
C
D
A
B
C
D
1
2
3
4
1
2
3
4
1
2
3
4
Away from magnet
Towards the magnet
Upwards
Downwards
A transformer has 100 turns in the primary coil and 25 turns in the secondary coil. When a 120 V is applied to the primary coil, what is the voltage in the secondary coil?
480V
30V
20V
450V
A transformer having turns ratio of 300 : 2400. What type of transformer is this?
Step down transformer
Ideal transformer
Step up transformer
Why transformers work with A.C. current but not D.C.
A.C current produces changing magnetic field.
D.C current produces changing magnetic field.
D.C current is weak
A.C current is powerful
A step-up transformer is supplied with 100 V from a DC supply. What will the output voltage be?
(a)
Choose the correct statement:
The ratio of the secondary voltage to the primary voltage is equal to the ratio of the primary turn to the secondary turn
The ratio of the primary current to the secondary current is equal to the ratio of the primary voltage to the secondary voltage
The ratio of the primary apparent power to the secondary apparent power is equal to the ration of the primary voltage to the secondary voltage
The ratio of the secondary current to the primary current is equal to the ratio of the primary turn to the secondary turn
A
B
C
D
X only
Y only
X and Y
X and Z
A
B
C
D
Along magnetic field
from X to Y
Out of the paper
Turns about the axis XY
It does not move at all
It moves upwards, out of the magnetic field
It turns to vertical position and eventually stops there
it turn to vertical position and them comes back to the horizontal position
A
B
C
D
The diagram shows a simple DC electric motor which is rotating.
Which change will make the motor rotate more quickly?
reversing the polarity of the magnets
reversing the battery
removing the magnets
using more powerful magnets
