KSSM FORM 5 TRANSFORMER

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