Magnetic Effects Of Current Question 113
Question: A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, the new value of the magnetic field is [CBSE PMT 2003]
Options:
A) B
B) 2 B
C) 4 B
D) B/2
Show Answer
Answer:
Correct Answer: A
Solution:
$ B={\mu_{0}}ni\Rightarrow \frac{B}{{{B}’}}=\frac{n}{{{n}’}}\times \frac{i}{{{i}’}}=\frac{1}{(1/2)}\times \frac{1}{2}=1\Rightarrow {B}’=B $
BETA
