Electromagnetic Induction

Energy Conversions

Energy can neither be created nor to be destroyed.

A solar cell converts solar energy into energy.

energy can be converted to Electrical energy by a Dry cell.

A wind mill is used to convert energy to Electrical energy.

Incandescent lamp convert Electrical energy to energy.

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Generation of Electricity

solenoidAccording to Michael Faraday, Electricity is generated when a Bar Magnet is inserted or pulled out of a Solenoid which is connected with a Galvanometer.

When pole of the magnet is moved into the solenoid, electric current in the solenoid is in anti clockwise direction at the nearer end of the magnet.

When North pole of the magnet is pulled out of the solenoid, the Galvanometer deflected to the (left/right) direction (see figure).

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Galvanometer Deflection

Question

Here there are some Experimental procedures with Bar Magnet and Solenoid. Select the procedure if there is deflection in the Galvanometer.

Answers

The magnet is stationary near the solenoid

North pole of the magnet is moved into the solenoid

The magnet is stationary inside the solenoid

The magnet is moved out of the solenoid.

The south pole of the magnet is moved into the solenoid

Magnet and solenoid are moved in the same direction at the same speed

The solenoid is moved keeping the magnet stationary

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Current increases

Check the following situations about the increase in current in the Galvanometer in the case of EM induction experiment.

Question 1

Number of turns increased in the Solenoid

Question 2

Bar magnet is fully inserted in the Solenoid

Question 3

Strong magnet is used

Question 4

Magnet/solenoid moves with greater speed

Electromagnetic Induction

Whenever there is a relative motion between the magnet and the solenoid, there is flow of electricity. According to Michael Faraday

Whenever there is a in the magnetic flux linked with a coil, an is induced in the coil. This phenomenon is electro-magnetic induction

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Fleming's right hand rule

It is the relation between the direction of magnetic field, the direction of movement of the conductor and the direction of induced current

Imagine a conductor moving perpendicular to a magnetic field.


Stretch the forefinger, middle finger and the thumb of the right hand in mutually perpendicular directions.

If the fore finger represents the direction of ,

and the thumb represents the direction of ,

then, the middle finger represents the direction of

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Electric Current Generator

When coil rotates about its own axis which is placed in a Magnetic field, Magnetic flux linked with the coil changes hence emf is induced

slipsplit

ring commutator is used in AC generator and rings are used to get DC

A current that flows only in one direction continuously is a current . Current that changes direction at regular
intervals of time, is an current

Generator is a device that converts energy into electrical energy by making use of electromagnetic induction

is an arrangement of insulated conducting wire wound on a soft iron core. This can be made to rotate about an axis.

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Select Correct statements

Question

acIn AC

Answers

Value and Direction of current changes continuously

Value and direction of current do not change

No Change in the direction of the current but its value changes

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Question

battery DC from Battery

Answers

Value and Direction of current changes continuously

Value and direction of current do not change

No Change in the direction of the current but its value changes

Feedback

Question

dcDC from Generator

Answers

Value and Direction of current changes continuously

Value and direction of current do not change

No Change in the direction of the current but its value changes

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Mutual Induction

The coil into which we give current for the production of magnetic field is the primary coil and the coil in which induced emf is generated is the secondary coil

When the strength or direction of the current in coil changes, the magnetic flux around it changes. As a result, an is induced in the secondary coil. This phenomenon is the mutual induction

A is a device that works on the principle of mutual induction

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Transformer

Transformer is a device for increasing or decreasing the voltage of an AC. Check the following statements

Question 1

Transformer can't be worked with DC

Question 2

If there is no energy loss in transformer the power in the primary and in the secondary are equal

Question 3

In a step up transformer the voltage in the secondary coil is more and the current is less

Question 4

Number turns in the secondary coil is high in the case of step-down transformer

Question 5

In step-up transformer, thin wires are used in the Primary coil

self induction

Inductors are coils used to oppose the changes in electric current in a circuit.

They are used to reduce current in a circuit to the desired value without loss of power

The change in magnetic flux due to the flow of an AC in a solenoid will generate a emf in the solenoid in a direction to that applied to it.

This phenomenon is known as the self induction

An inductor is an insulated copper wire wound in a shape

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Moving Coil Microphone

Main parts of Moving Coil Microphone are Diaphragm, Voice coil and Permanent magnet. Principle behind the working of this device is Electro-magnetic Induction

The voice coil is situated in a field. The diaphragm connected to the voice coil in accordance with the sound waves falling on it.
As a result, signals corresponding to the sound waves are generated in the voice coil.
In the microphone, (sound) energy is converted into electrical energy

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Power Transmission and Distribution

The principle of electromagnetic induction is used worldwide to generate electricity on a large scale

generators are used to produce electricity for the purpose of distribution.

Phase Generators have only one set of coil in between the poles of a field magnet.

In three phase generators, three armature coils are arranged around the field magnet at an angular separation of degree.

Heat loss can be reduced by transmitting power with current ( voltage) for long distances.

So in Power stations step transformers are used and step transformers are used in sub stations.

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Household Electrification

power

is the device where the electric line reaching our home connected first.

Watt-Hour meter is the starting point of .

Fuse is the security device which is connected at the .

Household devices are connected in .

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DropDown Activity

Find the relation of first pair and fill in the blank

Moving coil microphone :
Loud speaker :

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