A) 0.4 s
B) 0.314 s
C) 0.2 s
D) 0.625 s
Correct Answer: C
Solution :
Energy stored in inductor \[U=\frac{1}{2}L{{i}^{2}}\] \[\Rightarrow \] \[32=\frac{1}{2}L{{(4)}^{2}}\] \[\Rightarrow \] \[L=4\,H\] Rate of heat loss \[A={{i}^{2}}R\] \[320={{(4)}^{2}}R\] \[\Rightarrow \,\,R=20\,\Omega \] Time constant \[t=\frac{L}{R}=\frac{4}{20}=\frac{1}{5}=0.2\,s\]You need to login to perform this action.
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