Electro Magnetic Induction And Alternating Currents Question 348

Question: A 50 volt potential difference is suddenly applied to a coil with $ L=5\times {{10}^{-3}} $ henry and $ R=180,ohm $ . The rate of increase of current after 0.001 second is [MP PET 1994]

Options:

A) 27.3 amp/sec

B) 27.8 amp/sec

C) 2.73 amp/sec

D) None of the above

Show Answer

Answer:

Correct Answer: D

Solution:

The rate of increase of current

$ =\frac{di}{dt}=\frac{d}{dt}i_{0}( 1-{{e}^{-Rt/L}} )=\frac{d}{dt}i_{0}-\frac{d}{dt}i_{0}{{e}^{-Rt/L}} $

$ =0-i_{0}{{e}^{-Rt/L}}.\frac{d}{dt}( -\frac{Rt}{L} )=i_{0}\frac{R}{L}{{e}^{-Rt/L}} $

$ =\frac{50}{180}\times \frac{180}{5\times {{10}^{-3}}}\times {{e}^{-(180\times 0.001)/(5\times {{10}^{-3}})}} $ $ =10^{4}\times {{e}^{-36}}A/\sec $



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