Question

Name the apparatus that works on the principle of electromagnetic induction.

Hint:

Any device that converts mechanical energy to electrical energy (generator) or electrical energy to mechanical energy (motor) typically works on electromagnetic induction. Transformers are pure examples of mutual induction without moving parts.

Answer 1

Electromagnetic Induction:  

Electromagnetic induction is the phenomenon of producing an electromotive force (EMF) or voltage across a conductor when it is exposed to a changing magnetic field. 

This principle was discovered by Michael Faraday in 1831. 

Faraday’s Law of Electromagnetic Induction: 

The induced EMF is equal to the negative rate of change of magnetic flux: 

$$ \mathcal{E} = - \frac{d\Phi_B}{dt} $$ 
where:

• $\mathcal{E}$ = Induced EMF
• $\Phi_B$ = Magnetic flux

Magnetic flux is given by: 

$$ \Phi_B = B A \cos\theta $$ 
where:

• $B$ = Magnetic field
• $A$ = Area of the loop
• $\theta$ = Angle between magnetic field and normal to surface

Apparatus Working on Electromagnetic Induction: 

1. Electric Generator (Dynamo):

• Converts mechanical energy into electrical energy.
• When a coil rotates in a magnetic field, magnetic flux changes and EMF is induced.
• Used in power plants, alternators, and portable generators.

2. Transformer:

• Transfers electrical energy between two circuits.
• Works on the principle of mutual induction.
• Used to step up or step down AC voltage.

3. Induction Motor:

• Converts electrical energy into mechanical energy.
• The rotating magnetic field of the stator induces current in the rotor.
• Widely used in fans, pumps, and industries.

4. Induction Cooktop:

• Uses electromagnetic induction to heat cooking vessels.
• Changing magnetic field induces eddy currents in the metal pan.
• Heat is produced due to electrical resistance.

5. AC Motor:

• Works on electromagnetic induction to produce rotation.
• Used in appliances and heavy machinery.

6. Induction Coil:

• Generates high voltage pulses from low-voltage DC.
• Used in spark plugs and ignition systems.

7. Magnetic Flow Meter:

• Measures flow of conductive liquids.
• Voltage induced is proportional to fluid velocity.

8. Eddy Current Brakes:

• Used in trains and roller coasters.
• Motion in magnetic field induces eddy currents that oppose motion.

9. Induction Furnace:

• Used to melt metals.
• High-frequency AC induces eddy currents producing heat.

10. Tape Recorder / Hard Drive Read Head:

• Works on electromagnetic induction.
• Changing magnetic field induces voltage representing stored data.

11. Wireless Charger:

• Uses inductive coupling.
• Changing magnetic field in transmitter coil induces current in receiver coil.

Summary Table: 

 

Apparatus	Type of Induction	Application
Electric Generator	Self-induction	Power generation
Transformer	Mutual induction	Voltage conversion
Induction Motor	Rotating magnetic field	Industrial machinery
Induction Cooktop	Eddy currents	Cooking
AC Motor	Electromagnetic induction	Mechanical motion
Magnetic Flow Meter	Electromagnetic induction	Flow measurement
Eddy Current Brakes	Eddy currents	Braking systems
Wireless Charger	Inductive coupling	Wireless charging

Final Answer: 

Electric Generator, Transformer, Induction Motor, Induction Cooktop, AC Motor, Magnetic Flow Meter, Eddy Current Brakes, Wireless Charger, etc., work on the principle of electromagnetic induction.