# A Current of 2 a Enters at the Corner D of a Square Frame Abcd of Side 20 Cm and Leaves at the Opposite Corner B. a Magnetic Field B = 0.1 T Exists in the Space - Physics

Sum

A current of 2 A enters at the corner d of a square frame abcd of side 20 cm and leaves at the opposite corner b. A magnetic field B = 0.1 T exists in the space in a direction perpendicular to the plane of the frame, as shown in the figure. Find the magnitude and direction of the magnetic forces on the four sides of the frame.

#### Solution

Given:
A square frame abcd of side, = 20 cm
Electric current through the wire, I = 2 A
Magnetic field, B = 0.1 T
The direction of magnetic field is perpendicular to the plane of the frame, coming out of the plane.
As per the question, current enters at the corner d of the square frame and leaves at the opposite corner b.
Angle between the frame and magnetic field, θ = 90˚
Magnetic force,
vecF = i vecl xx vecB
For wire da and cb,
|vecF| = ilBsin theta
|vecF| = ilBsin90°
= 2/2 xx 20 xx 10^-2xx 0.1
= 0.02 N
The direction of force can be found using Fleming's left-hand rule.
Thus, the direction of magnetic force is towards the left.
For wires dc and ab,
|vecF| = ilBsintheta
∴ |vecF| = ilBsin90^circ
= 2/2 xx 20 xx 10^-2xx0.1
= 0.02 N
The direction of force can be found using Fleming's left-hand rule.
Thus, the direction of magnetic force is downwards.

Concept: Force on a Moving Charge in Uniform Magnetic and Electric Fields
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#### APPEARS IN

HC Verma Class 11, Class 12 Concepts of Physics Vol. 2
Chapter 12 Magnetic Field
Q 8 | Page 230