A coil of inductance 8.4 mh and resistance 6 Ω is connected to a 12 V battery. The current in the coil is 1.0 A approximately after time

  • Option 1)

    500 ms
     

  • Option 2)

    20 ms

  • Option 3)

    35 ms

     

  • Option 4)

     1 ms

 

Answers (1)

 

Self Inductance -

An emf is induced in the coil or the circuit which oppose the change that causes it. Which is also known back  emf.

- wherein

 

 i=i_{0}(1-e^{-t/T})

\left [ T=\frac{1}{R}=\frac{8.4mH}{6\Omega }=1.4ms \right ]

i_{0}=\frac{e}{R}=\frac{12}{6}=2A

i=1A

=> 1=2(1-e^{-t/T})

=>e^{-t/T}=\frac{1}{2}

=> \frac{t}{T}=l_{n}2

=>t=(0.693)T

=> t=(0.693)T

=> t= 1ms


Option 1)

500 ms
 

Option is incorrect

Option 2)

20 ms

Option is incorrect

Option 3)

35 ms

 

Option is incorrect

Option 4)

 1 ms

Option is correct

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