A galvanometer has a full-scale deflection current of 5000 μA and a resistance of 600 Ω. What is the

JAMB Physics 2023 95 views

A galvanometer has a full-scale deflection current of 5000 μA and a resistance of 600 Ω. What is the value of the multiplier resistor required to convert the galvanometer into a voltmeter with a full-scale voltage of 80 V?

  1. 1.54 kΩ
  2. 15.4 kΩ ✓
  3. 154 kΩ
  4. 1540 kΩ

Explanation

Step 1: Identify given values and what to find
Given: I_g = 5000 μA = 5 × 10⁻³ A, R_g = 600 Ω, V = 80 V
Find: Multiplier resistance R

Step 2: Calculate total resistance needed
Formula: R_total = V/I_g
R_total = 80/(5 × 10⁻³) = 16000 Ω

Step 3: Calculate multiplier resistance
Formula: R = R_total – R_g
R = 16000 – 600 = 15400 Ω = 15.4 kΩ

Step 4: The answer is 15.4 kΩ

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