JEE Mains · Physics · STD 12 - Current electricity
- JEE Mains 2026
- Hard
- MCQ
The total length of potentiometer wire AB is 50 cm in the arrangement as shown in figure. If P is the point where the galvanometer shows zero reading then the length AP is _________ cm .

Pick an option to check your answer.
Answer & Solution
Correct Answer
(B) 30
Step-by-step Solution
Detailed explanation
\(\frac{6}{ R _{ AP }}=\frac{4}{ R _{ PB }} ;\)
\(\ell_{ AP }+\ell_{ PB }=50\)....(i)
\(\frac{ R _{ AP }}{ R _{ PB }}=\frac{\ell_{ AP }}{\ell_{ PB }}=\frac{3}{2}\)
\(\ell_{ AP }=\frac{3}{5} \times 50=30 cm\)
\(\ell_{ AP }+\ell_{ PB }=50\)....(i)
\(\frac{ R _{ AP }}{ R _{ PB }}=\frac{\ell_{ AP }}{\ell_{ PB }}=\frac{3}{2}\)
\(\ell_{ AP }=\frac{3}{5} \times 50=30 cm\)
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