magnets

poles

north
south

lines of force

electromagnets
electric motor
Faraday's Law
transformer

Qu. 2:
a) using formula primary voltage/primary turns = secondary voltage/sec. turns

secondary voltage = primary voltage/primary turns * sec. turns
secondary voltage = 12V/50*250 = 60V

b) using Ohm's Law, current = V/R = 60V/10ohms=6Amp
c) Power = current * voltage = 6A * 60V = 360 Watt

Qu 3:
a) using formula primary voltage/primary turns = secondary voltage/sec. turns

secondary turns = primary voltage/secondary voltage * primary turns
secondary turns = 6V/120V * 240 turns = 12 turns