A 50-turn circular coil with radius 4 cm is placed in magnetic field of 6000 G. An amount of 800 mA current passes through the circular coil and the area vector of plane makes 40o with the magnetic field. Torque (τ) acting on the coil is  ​

Explanation:

n=50,r=0.02mn=50,r=0.02m,

I=5AandB=0.20TI=5AandB=0.20T

τismaxiμmwhensinθ=90∘τismaxiμmwhensinθ=90∘

τmax=niabsin90∘=mbτmax=niabsin90∘=mb

=50×5×3.14×4×10−4×2×10−1=50×5×3.14×4×10-4×2×10-1

=6.28×10−2Nm=6.28×10-2Nm

Given τ=12×τmaxτ=12×τmax

⇒sinsinθ=12⇒sinsinθ=12 or sinθ=30∘sinθ=30∘

=∠betweenareavar→randmag≠ticfield=∠betweenareavar→randmag≠ticfield.

So angle between magnetic field and the plane of the coil

=90∘−30∘=60∘=90∘-30∘=60∘.

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia