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Question: The self inductance of a coil having 400 turns is 10 mH. The magnetic flux through the cross section...

The self inductance of a coil having 400 turns is 10 mH. The magnetic flux through the cross section of the coil corresponding to current 2 mA is

A

4 x 10-5 Wb

B

2 x 10-3 Wb

C

3 x 10-5 Wb

D

8 x 10-3 Wb

Answer

4 x 10-5 Wb

Explanation

Solution

Here, N = 400, L = 10 mH =10×103H= 10 \times 10 ^ { - 3 } \mathrm { H }

I=2 mA=2×103 A\mathrm { I } = 2 \mathrm {~mA} = 2 \times 10 ^ { - 3 } \mathrm {~A}

Total magnetic flux linked with the coil.

ϕ=NLI=400×(10×103)×2×103=8×103 Wb\phi = \mathrm { NLI } = 400 \times \left( 10 \times 10 ^ { - 3 } \right) \times 2 \times 10 ^ { - 3 } = 8 \times 10 ^ { - 3 } \mathrm {~Wb}magnetic flux through the cross section of the coil.

= Magnetic flux linked with each turn

=ϕN=8×103200=4×105 Wb= \frac { \phi } { \mathrm { N } } = \frac { 8 \times 10 ^ { - 3 } } { 200 } = 4 \times 10 ^ { - 5 } \mathrm {~Wb}