NEET · Physics · STD 12 - 4. Moving charges and magnetism
A 2 amp current is flowing through two different small circular copper coils having radii ratio \(1: 2\). The ratio of their respective magnetic moments will be
- A \(1:4\)
- B \(1:2\)
- C \(2:1\)
- D \(4:1\)
Answer & Solution
Correct Answer
(A) \(1:4\)
Step-by-step Solution
Detailed explanation
Magnetic moment \(M = I ( A )\)
\(M=I\left(\pi r^2\right) \)
\( \frac{M_1}{M_2}=\frac{I \pi r_1^2}{I \pi r_2^2}=\left(\frac{r_1}{r_2}\right)^2=\left(\frac{1}{2}\right)^2 \)
\( \frac{M_1}{M_2}=\frac{1}{4}\)
\(M=I\left(\pi r^2\right) \)
\( \frac{M_1}{M_2}=\frac{I \pi r_1^2}{I \pi r_2^2}=\left(\frac{r_1}{r_2}\right)^2=\left(\frac{1}{2}\right)^2 \)
\( \frac{M_1}{M_2}=\frac{1}{4}\)
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