Physics 2021 JAMB Past Questions - Question 39:  A current of 2.0A passes through a straight wire in a uniform magnetic force of density 2.0 × 10-³T. What force per unit length is exerted on the wire when it is inclined at 60o to the magnetic field?

Correct Answer

D

Explanation

To find the force per unit length exerted on the wire when it is inclined at 60 degrees to the magnetic field, you can use the formula:

F = B * I * L * sin(θ)

Where:
F = force per unit length
B = magnetic field density
I = current
L = length of the wire
θ = angle between the wire and the magnetic field

Plugging in the given values:
B = 2.0 × 10^-3 T
I = 2.0 A
θ = 60 degrees

F = (2.0 × 10^-3 T) * (2.0 A) * L * sin(60°)

Since sin(60°) = √3 / 2, we can simplify the equation:

F = (2.0 × 10^-3 T) * (2.0 A) * L * (√3 / 2)
F = 2.0 × 10^-3 T * 2.0 A * L * (√3 / 2)
F = 2.0 × 10^-3 T * 2.0 A * L * √3 / 2
F = 2.0 × 10^-3 T * A * L * √3

So, the force per unit length exerted on the wire when it is inclined at 60 degrees to the magnetic field is 2.0 × 10^-3 T * 2.0 A * L * √3.