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An ideal transformer has 100 turns in the primary and 500 turns in the secondary. If the primary voltage is 120V and the primary current is 2A, what is the secondary current?
20 A
10 A
0.4 A
5 A
A step-up transformer operates on a 220V line and supplies a load of 2A. The ratio of the primary and secondary windings is 1:25. Determine the current in the primary, assuming an ideal transformer.
50 A
0.08 A
27.5 A
110 A
A transformer has an efficiency of 80%. It works at 4 kW and 100 V. If the secondary voltage is 240 V, calculate the primary and secondary currents.
Primary current: 40 A, Secondary current: 20 A
Primary current: 50 A, Secondary current: 16.67 A
Primary current: 25 A, Secondary current: 33.33 A
Primary current: 60 A, Secondary current: 12.5 A
A step-up transformer increases the voltage. What happens to the current in an ideal transformer when the voltage is stepped up?
Decreases
Increases
Remains the same
Becomes zero
The core of a transformer is laminated to:
Reduce eddy current losses
Increase magnetic flux
Reduce hysteresis losses
Increase the efficiency of the transformer
A transformer has 500 turns in the primary coil and 1000 turns in the secondary coil. If the input voltage is 120V, the output voltage is:
240V
60V
120V
480V
Which of the following is NOT a factor affecting the efficiency of a transformer?
The frequency of the AC supply
Eddy current losses
Hysteresis losses
Copper losses in the windings
A transformer works on the principle of:
Self-induction
Mutual induction
Electromagnetic waves
Ohm's law
In an ideal transformer, which quantity remains constant?
Current
Voltage
Resistance
Power
A step-up transformer:
Increases both voltage and current
Decreases both voltage and current
Increases voltage and decreases current
Decreases voltage and increases current
