Moving Charges and Magnetism

Linear mass density of wire, λ=0.12kg∕m
Magnetic field, B=0.5T
Acceleration due to gravity, g=10m∕s2
The wire is suspended in air ⟶ magnetic force per unit length balances weight per unit length.
Step 1: Write force balance
For unit length of wire:
Magnetic force per unit length = Weight per unit length
So,
IB=λg
Step 2: Solve for I
I=‌

λg

B

Substitute:
I=‌

0.12×10

0.5

I=‌

1.2

0.5

=2.4A
Final Answer: I=2.4A
Option A - 2.4 A