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Effects of Electric Current

The flow of electric current causes the following effects in a conductor:
  1. heating effect,
  2. chemical effect,
  3. magnetic effect.
Heating Effect
Electric current flowing in an electric iron produces heat. We use this heat for ironing the clothes. An electric current, therefore, produces a heating effect. Whenever an electric current flows through a wire (conductor), a small amount of electrical energy is converted into heat energy. This is called the heating effect of electric current. Heating effect is due to the resistance of the conductor. The conducting wires made of certain substances produce relatively more heat than others of the same dimension depending on the resistance. This effect of electric current is utilised in appliances such as electric stove, boiler, electric fuse, electric iron, electric bulb, water heater, etc.
The heat produced in a conductor, when a current flows through it, is found to depend directly on the following factors:
  1. strength of the current,
  2. resistance of the conductor and
  3. time for which the current flows.
Mathematical expression for the heat produced is given by
Q = VIt
= I2Rt
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The expression U = VIt is called Joule and Lenz’s law.

Magnetic Effect of Electric Current

In 1820, Oersted performed an experiment which demonstrated the magnetic effect of electric current. He placed a compass needle parallel to a straight conductor carrying current and found that the needle was deflected. On reversing the current, the needle deflected in the opposite direction. Thus, Oersted concluded that a magnetic field is created around a conductor carrying the electric current. This is known as the magnetic effect of electric current.
Instruments that work based on magnetic effect of electric current are galvanometer, ammeter, voltmeter, etc. The commonly used appliances such as electric fan, telephone, microphone, etc., have components that work on magnetic effect of the electric current.
The direction of the magnetic field due to a straight current-carrying conductor is given by
  1. right-hand clasp rule,
  2. Maxwell’s cork screw rule and
  3. Ampere’s swimming rule.

Mechanical Effect of an Electric Current

A moving charge or a current-carrying conductor placed in a magnetic field experiences a mechanical force. This is referred to as the mechanical effect of an electric current.
If a charge q moves at an angle θ with the direction of a magnetic  field of induction B with a speed V, then the magnitude of the mechanical force on it is given by the equation F = Bq V sin θ.

Chemical Effect of an Electric Current
We know that in electric cells, chemical energy gets converted into electrical energy. The opposite activity is also possible. This means that electrical energy can be used to produce chemical reactions. Some chemical substances in a molten state or in their solution form allow the current to pass through them.

Some examples are sodium chloride solution, copper sulphate solution, sulphuric acid, etc. Such substances are called electrolytes. When an electric current is passed through such chemical compounds, they get decomposed into ions. This process is called electrolysis. Hence, electric current decomposes a few compounds in a molten state or in their aqueous form. This shows that the electric current produces chemical effects.

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