Answer:
Explanation:
The magnetic force due to lower rod must be equal to weight of upper rod for equilibrium .
magnetic field due to lower rod on upper rod
= ( μ₀ / 4π ) x(2i / r ) , i is current , r is distance between rod
= 10⁻⁷ x 2 x 15 / 1.5 x 10⁻³
= 20 x 10⁻⁴ T
force on the upper rod
= B i L , B is magnetic field , i is current in second rod and L is its length
= 20 x 10⁻⁴ x 15 x .50
= 150 x 10⁻⁴ N
= .015 N
This force can balance a wire having weight equal to .015 N .
= .00153 kg
= 1.53 g .
wire should weigh 1.53 g .
