Pre Assessment May 2025 Transformer Um Ghafa School

In an ideal transformer, if the primary coil has 100 turns and the secondary coil has 200 turns, what is the voltage transformation ratio?

• 1:2

• 2:1

• 1:1

• 100:200

Why can't a transformer work with DC supply?

• Because DC has high resistance

• Because there is no magnetic field in DC

• Because DC causes constant magnetic flux, which doesn't induce EMF

• Because DC creates rotating magnetic fields

A transformer with a turns ratio of 1:10 is connected to a 230 V supply. What type of transformer is it, and what is the output voltage?

• Step-up, 23 V

• Step-down, 23 V

• Step-up, 2300 V

• Step-down, 2300 V

If a transformer has 95% efficiency and delivers 950 W of output power, what is the input power?

• 902.5 W

• 950 W

• 1000 W

• 1050 W

What is the working principle of a transformer

• Electromagnetic Induction

• Mutual Induction

• Self Induction

• Induction