JEE Mains · Physics · STD 12 - 3. current electricity
In an electric circuit, a cell of certain emf provides a potential difference of \(1.25\, {V}\) across a load resistance of \(5\, \Omega .\) However, it provides a potential difference of \(1\, {V}\) across a load resistance of \(2\, \Omega\). The \(emf\) of the cell is given by \(\frac{x}{10} v\). Then the value of \(x\) is ..... .
- A \(10\)
- B \(15\)
- C \(32\)
- D \(30\)
Answer & Solution
Correct Answer
(B) \(15\)
Step-by-step Solution
Detailed explanation
Terminal voltage \(v=i R=\frac{E R}{R+r}\) \(1^{s t} \rightarrow 1.25=\frac{E(5)}{5+r} . .(i)\) \(2^{n d} \rightarrow 1=\frac{E(2)}{2+r}\, \cdots \text { (ii) }\) By \((i)\) and \((ii)\) \(r=1 \,\Omega, E=\frac{3}{2} \,V=\frac{15}{10}\, \text { volt }\) \(\Rightarrow {x}=15\)
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