study material-physics-magnetism
Electromagnetics - 4
Illustration:
Q1. A change q moves in a circular path of radius r with a speed of v. Calculate the induction of the magnetic field produced at the centre of the circle.
Solution: The equivalent current in the circular path is
I = 
B = 
Q2. The coil of a galvanometer has 500 turns and each turns has an avg. area 3 x 10-4 m2. calculate the magnetic moment of the coil when a current of 0.5 A passes throgh it. If a torque of 1.5 Nm is required for this coil carrying same current to set it parallel to a magnetic field. Calculate the magnetic field.
Solution: µ = NIA
                = 500 x 0.5 x 3 x 10-4
                = 0.075 Am2
Also 
or |
| = µB sin
where = angle between B and A
Here = 900
= µB sin900
B = 
= 20 T
ASSIGNMENTS:
Easy:
E1. Find the magnetude of magnetic field at point P due to the current carrying wire as shown.
Solution:
1 = - 300, 2 = 600 
E2. Shown infigure is a conductor carrying current I. Find the magnetic field intensity at the point O.
Solution: B =
[Due to an are] 
E3. What is the work done in transferring the wire from position (1) to position(2) ?
Solution:
The 'd' magnetic moment of the loop = I2l dr
Br =
Ur =
-
U = work done - (U2 - U1)