Same chapter2 marksDifficulty: Medium
Why does a transformer not work on a direct-current supply?
Electromagnetism
3 marksDifficulty: Medium
State the principle of an a.c. generator and name the law it depends on.
Original Khojo Papers practice question — not from a past board paper.
Answer
When a coil is rotated in a magnetic field the magnetic flux linked with it changes, and an e.m.f. is induced in it. This is electromagnetic induction, described by Faraday's laws.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
The induced current reverses each half revolution, which is why the output is alternating.
Related questions
From the same topic and chapter, at a similar level.
Same chapter3 marksDifficulty: Medium
What is the function of the split-ring commutator in a d.c. motor?
Electromagnetism
Same chapter3 marksDifficulty: Medium
Why is soft iron used for the core of an electromagnet and steel for a permanent magnet?
Electromagnetism
Same chapter3 marksDifficulty: Medium
A transformer has 200 turns in its primary and 1000 turns in its secondary. If the primary is connected to a 220 V a.c. supply, find the secondary voltage and state the type of transformer.
Electromagnetism
Same chapter3 marksDifficulty: Medium
State the principle of an electric motor and name the rule used to find the direction of rotation.
Electromagnetism
Same chapter1 markDifficulty: Medium
A transformer with more turns in the secondary than in the primary is a:
Electromagnetism