Q152 / 160 · TS EAMCET 2021 (05 Aug Shift 1) · Physics

A coil of resistance 50 Ω is connected across a 5.0 V battery. If the current in the coil is found to be 50 mA after the time t=0.1 s battery is connected, then the inductance of the coil is

  • Correct answer
    A
    5ln2
  • B
    10ln(2)
  • C
    5e4
  • D
    10e4

Solution

The values are given, R=50 Ω, ε=5 V, i=50×10-3 A and t=0.1 s, the equation of, 
 i=i01-e-t×RL⇒50×10-3=i01-e-0.1×50L

Now use the relation between current and voltage, i0=εR=550, 

it means, 
⇒50×10-3=5501-e-0.1×50L⇒50×10-2=1-e-0.1×50L⇒L=5ln2
 

Hence, the correct answer is option: 'A'.

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