Magnetic Effects Of Current Question 122
Question: Two wires of same length are shaped into a square and a circle. If they carry same current, ratio of the magnetic moment is [DCE 2002]
Options:
A) 2 : p
B) p : 2
C) p : 4.0
D) 4 : p
Show Answer
Answer:
Correct Answer: C
Solution:
Suppose length of each wire is l. $ r\propto \frac{1}{B} $ $ A_{circle}=\pi r^{2}=\pi {{( \frac{l}{2\pi } )}^{2}}=\frac{l^{2}}{4\pi } $ $ \because $ Magnetic moment $ M=iA $ $ \Rightarrow \frac{M_{square}}{M_{circle}}=\frac{A_{square}}{A_{circle}} $ $ =\frac{l^{2}/16}{l^{2}/4\pi } $ $ =\frac{\pi }{4} $
BETA
