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MHT CET · Physics · Magnetic Effects of Current

Two circular coils \(P\) and \(Q\) are made from similar wire, but radius of \(Q\) is twice that of \(P\). What should be the value of potential difference across them so that the magnetic induction at their centre may be same?

  1. A \(V_{q}=2 V_{p}\)
  2. B \(V_{q}=3 V_{p}\)
  3. C \(V_{q}=4 V_{p}\)
  4. D \(V_{q}=\frac{1}{4} V_{p}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(V_{q}=4 V_{p}\)

Step-by-step Solution

Detailed explanation

\(B_{1}=\frac{\mu_{0}}{4 \pi}\left[\frac{2 \pi I_{1}}{T_{1}}\right]\) and \(B_{2}=\frac{\mu_{0}}{4 \pi}\left[\frac{2 \pi I_{2}}{r_{2}}\right]\)
Since, \(\quad B_{1}=B_{2}\) and \(r_{2}=2 r_{1}, I_{2}=2 l_{1}\)
\(
\frac{V_{2}}{V_{1}}=\frac{I_{2} R_{2}}{I_{1} R_{1}}=\frac{2 I_{1}}{I_{1}} \times \frac{2 R_{1}}{R_{1}}=\frac{4}{1}
\)