Different ways to Induce Current in the Coil

Introduction: 

The electric potential produced by changing magnetic flux is called induced electric potential. The induced electric potential is also called electromotive force (Emf). The electromotive force (Emf) is the electric potential that is generated when there is a transfer of energy from one form to another. Like producing electrical energy by changing magnetic field. 

Whenever there is a change in the magnetic flux linked with a closed circuit, an emf produces a current known as induced current. However, it lasts only as long as the magnetic flux is changing. 

Explanation: 

A current gets induced in the coil when it is exposed to changing magnetic field. The magnetic field can be changed in various ways: 

Different ways to induce current: 

1. Moving the magnet and keeping the coil at rest: 

2. Moving the coil and keeping the magnet at rest: 

3. Keeping the coils at rest and changing current in a coil: 

4. Changing the area of a coil located in a magnetic field: 

Motional Emf 

An Emf that is developed in a conductor because of relative motion in a magnetic field is known as motional Emf. 

When a conductor moves in a magnetic field, the free electrons inside it experience a force and starts accumulating at the one end of the conductor, as a result, one end of the conductor becomes positively charged whereas the other end becomes negatively charged, and a potential difference is developed. This induced electric potential is known as motional emf. 

Factors on which motional Emf depend: 

• Motional Emf (E) increases with an increase in the magnetic field (B). 
• Motional Emf (E) increases with an increase in the velocity of the conductor (V). 
• Motional Emf (E) increases with an increase in the length of the conductor (L). 
• Motional Emf (E) also depends on the angle (θ) between V and B.

The formula for motional Emf (E): 

E α velocity of the conductor α V 

E α Magnetic field α B 

E α Length of the conductor α L 

E α the angle (θ) between the in the conductor and the magnetic field (B), E α sinθ 

E is maximum when θ = 90, E is minimum when θ = 0  

Thus, E = BVL sinθ 

When a moving conductor is placed in a magnetic field, an electric current is induced. This induced current is reversed if the conductor moves in the opposite direction or if the magnetic field is reversed. Thus, there is a relation between the direction of the conductor, magnetic field, and the current induced. There is a rule that can be used to know the relationship among them that is known as Fleming’s Right-hand rule. 

Fleming’s Right-Hand Rule 

According to Fleming’s Right-hand rule when the thumb, forefinger, and central finger are kept mutually perpendicular to each other then 

Thumb– shows the direction of motion of the conductor 

Forefinger– shows the direction of the changing magnetic field

 Middle finger – shows the direction of the induced current 

Summary

• An emfis produced when there is a change in the magnetic flux linked to a closed circuit. This emf is called induced emf and the current produced is known as induced current
• A current can be induced in the coil in various ways: .
• By changing the strength of a magnetic field •
• By changing the distance between the magnet and the conductor .
• By changing the area of the loop located in the magnetic field. .
• By changing current in a coil.
• Motional EMF: An EMF that is developed in a conductor as a result of relative motion in a magnetic field is known as motional EMF
• The formula for motional EMF
• (E): E a velocity of the conductor a V
• E a Magnetic field a B E a Length of the conductor a L
• E a the angle (2) between the in the conductor and the magnetic field (B), F a sine
• E is maximum when = 90,
• E is minimum when = 0 Thus, E = BVL Sine Fleming’s Right-Hand Rule
• According to Fleming’s Right-hand rule when the thumb, forefinger, and central finger are kept mutually perpendicular to each other then:
• Thumb-shows the direction of motion of the conductor Forefinger-shows the direction of the changing magnetic field
• Middle finger – shows the direction of the induced current