Physics-
General
Easy
Question
A solenoid has 2000 turns wound over a length of 0.30 m. The area of its cross-section is 
Around its central section a coil of 300 turns is wound. If an initial current of 2 A in the solenoid is reversed in 0.25s, the emf induced in the coil is
- 48 V
- 4.8 V
- 4.8
- 4.8
The correct answer is: 48 V
The induced emf is given by
…(i)
Where 
is coefficient of mutual inductance, 
is rate of change of current.
Also, mutual inductance of two coaxial solenoids is given by
…(ii)
From Eqs. (i) and (ii), we get
Given, 
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