Question

The coefficient of mutual inductance is 2H and induced e.m.f. across secondary is 2 kV. Current in the primary is reduced from 6 A and 3A. The time required for the change of current is ____________.

Options

• 2 x 10^-3 s

• 4 x 10^-3 s

• 3 x 10^-3 s

• 10^-3 s

Answer 1

The coefficient of mutual inductance is 2H and induced e.m.f. across secondary is 2 kV. Current in the primary is reduced from 6 A and 3A. The time required for the change of current is 3 x 10^-3 s.

Explanation:

M = 2H, e = 2kV = 2 x 10³ V

`Delta "I" = 6"A" - 3"A" = 3"A", Delta"t"  = ?`

`"e" = ("M" . Delta"I")/(Delta"t")`

`therefore Delta"t" = ("M". "DI")/"e"`

`= (2 xx 3)/(2 xx 10^3)`

`= 3 xx 10^-3  "s"`