A moving coil galvanometer allows a full scale current of 10 - 4   A . A series resistance of 2  …

A moving coil galvanometer allows a full scale current of 10-4 A . A series resistance of 2 ×104 Ω is required to convert the galvanometer into a voltmeter of range 0-5 V . Therefore, the value of shunt resistance required to convert the above galvanometer into an ammeter of range 0-10 mA is:
  1. 100 Ω
  2. 200 Ω
  3. 300 Ω
  4. 10 Ω

Solution

ig=10-4 A

 i=10×10-3 A

 RV=20 kΩ

igG+ig RV=5

igG=i-igRA
RA=igGi-ig=ig5-igRVi-igig
RA=5-igRVi-ig≈300  Ω

Asked in: JEE Main 2019 (10 Apr Shift 1)

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