Magnetic Effect of Electric Current

Bar magnet vs Electromagnet

Compare the figures

Solenoid

It is a Bar magnet and an Electromagnet.

We can use compass needle to find the of the magnetic field.

It is directed from the pole to pole in the outer region of the magnet.

Like poles (same polarity) and unlike poles .

Bar magnet is a magnet while electromagnet is a magnet.

The magnetic field lines of the bar magnet and that of the electromagnets are

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Electric current produces magnetic field

Magnetic field

Arrangement is a circuit above a pivoted magnetic needle in such  a way that the part AB of the conductor is parallel and close to the magnetic needle

When the direction of electric current is from A to B, The direction of the flow through it is from B to A

A magnetic field is developed around a carrying conductor. The magnetic needle is deflected as a result of the mutual action of this field and that around the magnetic needle.

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Right Hand Thumb Rule

Question

Right Hand Thumb Rule

The thumb points in the direction of the ..............

Answers

Current

Magnetic Field

Force

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Question

The direction in which the other fingers encircle the conductor gives the direction of the ........

Answers

Current

Magnetic Field

Electric Field

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Right Hand Screw Rule

It is similar to Right Hand Thumb Rule

 

If a right hand screw is rotated in such a way that its tip advances along the direction of the in the conductor, then the direction of rotation of the screw gives the direction of the around the conductor

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Solenoid

Study the figures

southnorth

A solenoid is an insulated wire wound in the shape of a helix.

The end of the solenoid at which current flows in the clockwise direction will be the Pole and the end at which current flows in the anticlockwise direction will be the Pole.

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Comparison of Bar magnet and Solenoid

Question

bar solenoid

Select the factors affecting the strength of the magnetic field of a solenoid carrying current.

Answers

Intensity of Electric Current

Number of turns

Medium (core) inside the solenoid

Area of cross-section of the loop

Direction of the Current

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Solenoid and Bar magnet

Solenoid is identical with Bar magnet. Analyse and compare the ability of solenoid and bar magnet to bring changes in permanency of the magnetism, polarity and the strength of the magnetism.

Question 1

Bar magnet shows permanent magnetism while Solenoid exhibits temporary magnetism

Question 2

Field lines are closed in both Bar magnet and Solenoid

Question 3

Magnetic lines are closed and starts from North pole to South pole inside the Bar magnet or Solenoid

Question 4

For both cases Magnetic field is uniform inside

Question 5

Strength of the Magnetism can't be changed in both cases

Fleming's Left Hand Rule

Fleming established a rule that will help to find out the direction of motion of the conductor in the devices making use of magnetic effect of electricity.

Hold the forefinger, the middle finger and the thumb of the left hand in mutually perpendicular directions.

If the forefinger indicates the direction of the

and the middle finger, the direction of the ,

then the thumb will indicate the direction of of the conductor.

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Electric Motor

f

Identify the parts of the Electric Motor

N,S poles
XY of rotation of the motor
ABCD
B1 , B2 brushes
R1 , R2

rings

When current is in the direction A to B ( or C to D), according to Fleming's Left Hand Rule, the arm AB moves in the direction ( arm CD in direction).

The split rings help to change the direction of current through the coil after every rotation

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Moving coil loud speaker

speaker

Read the paragraph below and fill in the missing words.

The pulses from a microphone are strengthened using an and sent through the voice coil of a loudspeaker.
The voice coil, which is placed in the field, moves to and fro rapidly, in accordance with the electrical pulses.

These movements make the diaphragm , thereby reproducing sound.

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