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
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 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
It is a device which converts mechanical energy into electrical energy. It is based on electromagnetic induction principle as explained above.
which current direction changes after equal intervals of time, then the current is called an alternating current (abbreviated as AC).
When the current flows in the same direction and does not change direction, it is called Direct current (DC)
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
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
Type of current/Potential Difference and Frequency
AC electric power of 220 V with a frequency of 50 Hz.
The wire, usually with red insulation cover, is called live wire (or positive)
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.
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.
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
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
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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