PHYSICS FORM 4 (NOTE)
CHAPTER 7: ELECTROMAGNETIC INDUCTION
7.2 FARADAY’S LAW OF INDUCTION
Definition
The faraday’s law of induction states that:The average EMF induced in a
conducting coil of N loops is equal to the negative of the rate at which the
magnetic flux through the coil is changing with time.
  N

t
The negative sign in the equation indicates that the direction of the induced
emf is such that it opposes the change in flux.
  B. A
Note;
Where;

is magnetic flux
B is the strength of the magnetic field
A is area perpendicular to magnetic field
Real – life applications of Faraday’s Law
1.
2.
3.
4.
Induction stoves
Tape players
Metal detector
Transformers
Example 7.3
Consider a flat square coil with 5 turns. The coil is 0.50 m on each side,
and has a magnetic field of 0.5 T passing through it. The plane of the coil is
perpendicular to the magnetic field; the field points out of the page. Use
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Faraday’s Law to calculate the induced emf if the magnetic field is
increased uniformly from 0.5 T to 1 T in 10 s.
Solution
  N
  N
  N

t
 f  i
t
B f A  Bi A
   NA
t
B f  Bi 
t
1  0.5
  50.52
10
  0.0625V
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