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MHT CET · Physics · Magnetic Effects of Current

The strength of magnetic field at a perpendicular distance ' \(x\) ' near a long straight conductor carrying current ' \(I\) ' is ' \(B\) '. The magnetic. field at a distance \(\frac{\mathrm{X}}{3}\) from straight conductor will be

  1. A \(\frac{B}{3}\)
  2. B 3 B
  3. C \(\frac{\mathrm{B}^2}{9}\)
  4. D \(9 \mathrm{~B}^2\)
Verified Solution

Answer & Solution

Correct Answer

(B) 3 B

Step-by-step Solution

Detailed explanation

\(\begin{array}{ll} & \mathrm{B} \propto \frac{1}{\mathrm{r}} \\ & \therefore \\ \therefore & \frac{\mathrm{B}_1}{\mathrm{~B}_2}=\frac{\mathrm{r}_2}{\mathrm{r}_1} \\ \therefore & \frac{\mathrm{~B}}{\mathrm{~B}_2}=\frac{\frac{\mathrm{x}}{3}}{\mathrm{x}} \\ \therefore & \frac{\mathrm{B}}{\mathrm{B}_2}=\frac{1}{3} \\ \therefore & \mathrm{~B}_2=3 \mathrm{~B}\end{array}\)