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NEET 2003

Exam: NEET
Year: 2003
Subject: Physics
Chapter: Magnetic Effects of Current

NEET 2003 · Physics · Magnetic Effects of Current

A long solenoid carrying a current produces a magnetic field B...

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

\mathrm{cm}

is halved, the new value of the magnetic field is:

Options

A $\frac{B}{2}$
B $B$
C $2 B$
D $4 B$

Correct answer

B. $B$

Step-by-step solution

Magnetic field induction at point insides the solenoid of length

l

, having

n

turns per unit length carrying current

i

. is given by B=\mu_0 n i If

i

is double and

n

is halved then

B

remains same.

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