 # Magnetic Effect of Electric Current (Class 10)

Notes NCERT Solutions Assignments

## Magnetic Effect of Current

what is a magnetic effect of Current?
Electricity and Magnetism are related phenomenon. When an electric current is passed through metallic conductor, it generates a magnetic field around it.

Magnetic Field due to current through straight Conductor
Electric current through a straight Conductor generates magnetic field around it.
a)Magnetic Field intensity increases on the increasing the current in the conductor
b) Magnetic field decrease as the distance increase from the conductor
c) Magnetic Field direction can be find using Right Hand Thumb Rule

What is Right Hand Thumb rule?
When you are holding a current-carrying straight conductor in your right hand such that the thumb points towards the direction of current. Then your fingers will wrap around the conductor in the direction of the field lines of the magnetic field Magnetic Field due to a Current through a Circular Loop
a) As with straight conductor, the magnetic field lines would be in the form of concentric circles around every part of the periphery of the conductor.
b) The magnetic field would be stronger near the periphery of the loop as magnetic field lines tend to remain closer when near the conductor.
c) The magnetic field lines would be distant from each other when we move towards the centre of the current carrying loop. At the centre, the arcs of big circles would appear as straight lines

Magnetic Field due to current through a coil having number of turns
We know that the magnetic field produced by a current-carrying wire at a given point depends directly on the current passing through it and the current in each circular turn has the same direction
Therefore, Magnitude of magnetic field gets summed up with increase in the number of turns of coil. If there are ‘n’ turns of coil, magnitude of magnetic field will be ‘n’ times of magnetic field in case of a single turn of coil.
Solenoid
A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is called a solenoid
Magnetic Effect of Current carrying Solenoid
A current carrying solenoid produces similar pattern of magnetic field as a bar magnet. One end of solenoid behaves as the north pole and another end behaves as the south pole. Magnetic field lines are parallel inside the solenoid; like a bar magnet; which shows that magnetic field is same at all points inside the solenoid
Electromagnet
When a piece of magnetic material, like soft iron is placed inside a solenoid,the  strong magnetic field produced inside a solenoid magnetise the soft iron and it behaves like strong magnet. The magnetism in the soft iron is temporary and it becomes null when the current is switched off. This type of magnet is called Electromagnets. So electromagnets are temporary magnets

## Force on a current carrying conductor in a Magnetic Field

When a current carrying, conductor is placed in a magnetic field, it experienced a force. The direction of force depends on the direction of the current and direction of the Magnetic Field. The direction of the force can be found using Fleming Left hand rule

Fleming Left hand rule
Stretch the thumb, forefinger and middle finger of your left hand such that they are mutually perpendicular. If the first finger points in the direction of magnetic field and the second finger in the direction of current, then the thumb will point in the direction of motion or the force acting on the conductor Electric Motor
An electric motor is a device which works on the above principle. Here the electrical energy is converted to mechanical energy. Here a current carrying conductor is placed in the magnetic field and force acts on the conductor and it rotates and do the mechanical work.
This is used in electric fans

## Electromagnetic Induction

Electromagnetic induction is the production of induced current in a coil placed in a region where the magnetic field changes with time.
The magnetic field may change due
a) relative motion between the coil and a magnet placed near to the coil.
b) If the coil is placed near to a current-carrying conductor, the magnetic field may change either due to a change in the current through the conductor or due to the relative motion between the coil and conductor.
The direction of the induced current is given by the Fleming’s right-hand rule.

Fleming’s Right Hand rule
Stretch the thumb, forefinger and middle finger of right hand so that they are perpendicular to each other. If the forefinger indicates the direction of the magnetic field and the thumb shows the direction of motion of conductor, then the middle finger will show the direction of induced current Electric Generator
It is a device which converts mechanical energy into electrical energy. It is based on electromagnetic induction principle as explained above.

AC Current
which current direction changes after equal intervals of time, then the current is called an alternating current (abbreviated as AC).

Direct Current
When the current flows in the same direction and does not change direction, it is called Direct current (DC)

AC generator
Electric Generator can be used to generate both the AC and DC current. When it is designed to produce AC current, it is called AC generator

DC generator
Electric Generator can be used to generate both the AC and DC current. When it is designed to produce DC current, it is called DC generator

Facts about AC and DC currents
a) Most power stations constructed these days produce AC.
b) In India, the AC changes direction after every 1/100 second, that is, the frequency of AC is 50 Hz.
c) An important advantage of AC over DC is that electric power can be transmitted over long distances without much loss of energy
Galvanometer
A galvanometer is an instrument that can detect the presence of a current in a circuit. The pointer remains at zero (the centre of the scale) for zero current flowing through it. It can deflect either to the left or to the right of the zero mark depending on the direction of current

## Domestic Electric Circuits

 S.no Terms Descriptions 1 Type of current/Potential Difference and Frequency AC electric power of 220 V with a frequency of 50 Hz. 2 Live Wire The wire, usually with red insulation cover, is called live wire (or positive) 3 Neutral Wire The wire, with black insulation, is called neutral wire (or negative). In our country, the potential difference between the Live wire and Neutral Wire is 220 V. 4 Earth Wire It has green insulation and this is connected to a metallic body deep inside earth. It is used as a safety measure to ensure that any leakage of current to a metallic body does not give any severe shock to a user. 5 Different Circuit used in the Home Supply Two separate circuits are used 1) 15 A current rating for appliances with higher power ratings such as geysers, air coolers, etc. 2) 5 A current rating for bulbs, fans, etc 6 Appliance circuit a) Each appliance has a separate switch to ‘ON’/‘OFF’ the flow of current through it. b) Each appliance has equal potential difference; they are connected parallel to each other 7 Electric Fuse a) A fuse in a circuit prevents damage to the appliances and the circuit due to overloading b) electric fuse prevents the electric circuit and the appliance from a possible damage by stopping the flow of unduly high electric current. c) Fuse is based on The Joule heating that takes place in the fuse melts it to break the electric circuit d) Tin-lead alloy is general used to make fuse wire

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Given below are the links of some of the reference books for class 10 Science.

You can use above books for extra knowledge and practicing different questions.

### Practice Question

Question 1 Which among the following is not a base?
A) NaOH
B) $NH_4OH$
C) $C_2H_5OH$
D) KOH
Question 2 What is the minimum resistance which can be made using five resistors each of 1/2 Ohm?
A) 1/10 Ohm
B) 1/25 ohm
C) 10 ohm
D) 2 ohm
Question 3 Which of the following statement is incorrect? ?
A) For every hormone there is a gene
B) For production of every enzyme there is a gene
C) For every molecule of fat there is a gene
D) For every protein there is a gene

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