Showing posts with label Electric Current. Show all posts
Showing posts with label Electric Current. Show all posts

Thursday, October 25

Heating Effects of Electric Current

Introduction to heating effects of electric current:

When we apply potential difference accross two ends of wire, an electric is set up in the wire.  Such a current is due to motion of free electrons in the wire.  During the motion of electrons they collide with each other and also with ions in the wire.  Due to these collisions kinetic energy of electrons decreases.  This loss in kinetic energy appears as heat and temperature of wire rises.  The amount of heat produced depends on (1) the current passing through the wire  (2) the resistance of the wire and 3) time for which current is passed.
Having problem with Electric Dipole Moment keep reading my upcoming posts, i will try to help you.
The amount of heat produced in a conductor is given by the formula H =I2Rt  Joules, where I is the current flowing through the conductor, R is the resistance of the conductor and t is the time for which the current passes through the conductor.

This mathematical equation can be stated in the form of a law which is known as Joule's law.

It states that " the quantity of heat generated (H) in a conductor of resistance (R), when current (I) flows through for time (t) is directly proportional to

i)  the square of the current

ii) the resistance of the conductor

iii) the time for which the current flows.

Applications of Heating Effect of Electric Current:

The heating effect of electric current has many practical applications.  It is used in many domestic appliances such as an electric heater, an electric iron, a geyser, lectric oven etc.

1)  An electric bulb contains a thin filament of metal like tungsten.  It has high melting point.  When current passes through the filament it is heated to high temperature and emits light.  This is the principle on which electric incandescent light bulb works.

2)  An lectric iron used for ironing clothes consists of a coil of high resistance covered by insulating mica sheets and kept inside heavy metal block.  When electric current passes through the coil it gets heated.  The iron metal block gets heated and can be used for ironing clothes.

3)  An important application of heating effect of electric current is a safety device known as "fuse".  Fuse is usuaaly made up of alloys of lead and tin.  It has very low melting point.  It melts with small rise in temperature.  Its diameter is such that it melts when a current passing through it exceeds certain value.  When excess current passes through fuse due to some accident such as short circuit, the wire melts and circuit immediately breaks down.  When shorcircuit occurs, high current flows through the circuit, the fuse wire gets heated up and melts.  The cicuit is broken and current stops flowing.

4) In industry soldering, welding, cutting, drilling and working of electric furnaces are based on heating of electric current.

5) In surgery, a fine heated platinum wire is used for cutting tissues much more efficiently than knife.