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KCET · Physics · Current Electricity

A car has a fresh storage battery of emf \(12 \mathrm{~V}\) and internal resistance \(2 \times 10^{-2} \Omega\). If the starter motor draws a current of \(80 \mathrm{~A}\). Then, the terminal voltage when the starter is On is

  1. A \(12 \mathrm{~V}\)
  2. B \(10.4 \mathrm{~V}\)
  3. C \(8.4 \mathrm{~V}\)
  4. D \(9.3 \mathrm{~V}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(10.4 \mathrm{~V}\)

Step-by-step Solution

Detailed explanation

Given, emf of battery, \(E=12 \mathrm{~V}\)
Internal resistance, \(r=2 \times 10^{-2} \Omega\)
Current, \(I=80 \mathrm{~A}\)
\(\therefore\) Terminal voltage when starter is \(\mathrm{ON}\) is given as
\(\begin{aligned}
V &=E-I r \\
&=12-80 \times 2 \times 10^{-2} \\
&=12-1.6=10.4 \mathrm{~V}
\end{aligned}\)