The terminals of a battery of emf 24.0 V and internal resistance of 1.0 Ω is connected to an externa

JAMB Physics 2023 275 views
Source: JAMB · 2023

The terminals of a battery of emf 24.0 V and internal resistance of 1.0 Ω is connected to an external resistor 5.0 Ω. Find the terminal p.d.

  1. 12.0 V
  2. 18.0 V
  3. 20.0 V ✓
  4. 16.0 V
Explanation

First find current using I = EMF/(R + r) = 24/(5 + 1) = 4 amperes. The total resistance is internal plus external resistance.

Terminal voltage equals EMF minus voltage drop across internal resistance: V = EMF – Ir = 24 – (4 × 1) = 20 volts.

Some voltage is lost inside the battery due to internal resistance. The terminal voltage is always less than EMF when current flows.

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