Magnetic Effects Of Current Question 33
Question: The strength of the magnetic field at a point r near a long straight current carrying wire is B. The field at a distance $ \frac{r}{2} $ will be [MP PMT 1990]
Options:
A) $ \frac{B}{2} $
B) $ \frac{B}{4} $
C) 2B
D) 4B
Show Answer
Answer:
Correct Answer: C
Solution:
$ B\propto \frac{1}{r}\Rightarrow \frac{B_{1}}{B_{2}}=\frac{r_{2}}{r_{1}}\Rightarrow \frac{B}{B_{2}}=\frac{r/2}{r}\Rightarrow B_{2}=2B $
BETA
