WorksheetsKSSM FORM 5 TRANSFORMER
Total questions: 12
Worksheet time: 15mins
What is the concept used to explain the working principle of a transformer?
electromagnetic induction
Fleming's left hand rule
Maxwell's screw rule
resonance
Why must a transformer use soft iron core?
it is easily magnetized and demagnetized
it is stronger than hard iron
it is cheaper
it can become an electromagnet
primary coil of a transformer must be connected to ___________
A.C. power supply
D.C. power supply
bulb
resistor
why a transformer cannot be connected to direct current source?
direct current produce a constant magnetic flux
direct current is steady current
direct current can pass through a capacitor
direct current produce weaker magnetic flux
which statement is wrong about the working principle of a transformer?
direct current will be produced at the secondary coil
magnetic flux will be produced at the primary coil
frequency of A.C. at secondary coil = primary coil
which statement is wrong about an ideal transformer?
no loss of energy
100% efficiency
input power = output power
input current = output current
why must a transformer use copper wire for the coils?
low resistance
higher thickness
stronger material
high melting point
how to reduce the effect of eddy current in a transformer?
use laminated sheets of soft iron core
use a u-shaped soft iron core
wrap the soft iron core with insulators
heat the soft iron core
for a transformer, if the
primary voltage = 120 V
secondary voltage = 6 V
primary current = 0.25 A
secondary current = 4.80 A
what is the efficiency of the transformer?
96%
104.2%
20%
5.2%
hysteresis is ______________
loss of energy due to magnetization and demagnetization of soft iron core
loss of energy due to leakage of magnetic flux
loss of energy due to the high resistance of coil
loss of energy due to incomplete connection of the circuit
the number of turns for primary coil is 2000. what is the number of turns for the secondary coil?
50
40
60
30
the efficiency of the component in box X is 80%. Calculate the input current when the output power is 65 W.
0.34 A
5.6 A
0.55 A
0.32 A
