MHT-CET : Physics Entrance Exam

### MHT - CET : Physics - Electomagnetic Induction Formulae Page 1

‹‹ Previous  |  Page 1  |  Page 2  |  Next ››

1. Magnetic flux through a plane of coil

 (f) = . = BA cos q: where B = magnetic induction A = area of the coil q = angle between (normal to the plane) and .

2. Induced e.m.f.:

 e = - df dt

where  e

=

e.m.f. induced in a circuit

 df dt

= rate of change of flux through the circuit

3. e.m.f. induced in a straight moving conductor in a perpendicular magnetic field:

 e = Blv where e = induced e.m.f . B= uniform magnetic induction l = length of the conductor v = velocity of conductor (at right angles to the uniform magnetic induction )

4. e.m.f. induced in a metal rod rotating in a perpendicular magnetic field:

= B × p r2 f = BAf

 where B = magnetic induction r = length of the rod f = frequency of rotation of the rod.

5. Self induction:

(i) The flux linked with a coil is given by f = LI

 where L = self inductance of coil I = current flowing through the coil

 (ii) e.m.f. (self induced ) = - L dI dt

where

L = self inductance of coil

 dI dt

= rate of change of current in the coil.

6. Mutual induction:

The magnetic flux linked with the secondary (fs) is given by fs = MIp

 where M = mutual inductance Ip = Current flowing in the primary coil.

 e.m.f. induced in secondary = - M dIp dt

7. Earth coil:

(i) The angle of dip (d):

tand = Bv/BH

 where Bv = Vertical component of earth's magnetic field BH = horizontal component of earth's magnetic field

(ii) q = k
q

 where q = charge passing through the ballistic galvanometer q = throw of the galvanometer k = constant of the galvanometer

 (iii) kq = f1 - f2 R

 where q = throw of the galvanometer f1 - f2 = change in flux through the earth coil R = Total resistance of the circuit.

(iv) Determination of BH and Bv :

 BH = ( KR ) q1 Bv = ( KR ) q2 2NA 2NA

Where BH = horizontal component of earth's magnetic field

Bv = vertical component of earth's magnetic field
K = constant of the galvanometer
R = resistance of the circuit
N = number of turns of the coil
A = area of cross-section of the coil
q1 and q2 - deflection in the galvanometer

(v) If the coil is quickly rotated from
a1 to a2 , the induced charge is given by

 q = BnA (cosa1 - cosa2) R

where R = total resistance of the circuit containing coil.

a) If the coil is rotated through an angle 90°

 q = BnA R

b) If the coil is rotator rotated through an angle 180°

 q = 2BnA R

‹‹ Previous  |  Page 1  |  Page 2  |  Next ››

 Career in India | Jobs in India