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MHT CET · Physics · Magnetic Effects of Current

A long solenoid carrying a current produces a magnetic field B along its axis. If the number of turns per \(\mathrm{cm}\) is doubled and the current is made, \(\left(\frac{1}{3}\right)^{\text {rd }}\) then the new value of the magnetic field will be

  1. A \(\frac{B}{3}\)
  2. B \(3 \mathrm{~B}\)
  3. C \(2 \mathrm{~B}\)
  4. D \(\frac{2 \mathrm{~B}}{3}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{2 \mathrm{~B}}{3}\)

Step-by-step Solution

Detailed explanation

Magnetic field inside a solenoid is given by
\(
\mathrm{B}=\mu_0 \mathrm{nI}
\)
If \(\mathrm{n}\) is doubled and \(\mathrm{I}\) is made \(\left(\frac{1}{3}\right)^{\mathrm{rd}}\), the value of \(\mathrm{B}\) will become \(\frac{2}{3} \mathrm{~B}\)