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  • A small loop of wire of area A = 0.01  , and resistance <img alt="R= 20 \Omega" src="http://entrancecorner

A small loop of wire of area A = 0.01 m^2 , and resistance R= 20 \Omega is initially kept in a uniform magnetic field B in such a way that the field is normal to plane of the loop .    when it is pulled out of the magnetic field , total charge of q = 2 \times 10 ^{-5}C flows through the coil . The magnitude of the field B is 

Option: 1

40 \times 10^{-3} T


Option: 2

4 \times 10^{-3} T


Option: 3

20 \times 10^{-3} T


Option: 4

2 \times 10^{-3} T


Answers (1)

best_answer

As we have learned

Faraday’s Second Law -

The induced emf is given by rate of change of magnetic flux linked with the circuit.

-

 

 

Magnetic flux \phi = BA

When it is pulled out of magnetic field change in flux \Delta \phi = BA

Acc. to faradays law 

\varepsilon = \frac{-\Delta \phi }{\Delta t}

Current induced in loop is 

i = \frac{\varepsilon }{R}= \frac{-1}{R}\frac{\Delta \phi }{\Delta t}

charge flown , 

q= i \Delta t = \frac{\Delta \phi }{R}

2 \times 10 ^{-5} = \frac{1}{20 } \times B\times 0.01

B = 40 \times 10^{-3}T

 

 

 

 

Posted by

Shailly goel

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