When electric current flows in a circuit,it produces various effects such as
- Heating Effect
- Luminous Effect
- Chemical Effect
- Magnetic Effect
Out of the above four effects Heating effect and magnetic effect are predominant.
In every electric circuit there is a resistance which opposes the flow of current.In order to overcome this resistance and for flow of current, an energy is expended. Here the expended energy appears as heat, causing the heating effect.
The expended power is given by
Where I is the current
R is the resistance..
When a current flows through a conductor it affects the magnetic materials near it or surrounding it.
We can prove this effect with a simple experiment.
Take a flat cardboard and pass a conductor through the board.Connect a battery to the free end of the conductor. Place some iron filings over the cardboard in random fashion.
Now,when no current flows through the circuit the iron filings remain as you placed with out any order(in random manner)
When supply is given using a battery and when current flows through the circuit,you can see the iron filings arranged in concentric circular fashion. This is due to the magnetic effect produced by current.
Now You might ask why the iron filings are arranged in concentric circular fashion..
Consider a simple example... When you throw a stone into a well the wave propagates in the form of concentric circles. similarly when current flows the iron filings are arranged in concentric circular fashion.
From this experiment we can conclude that:
- A conductor carrying current produces a magnetic field.
- Direction of magnetic field depends on direction of current flow.
- The field is in the form of concentric circle.
- The direction of field is perpendicular to the direction of conductor.
Consider the tip of right handed screw. If the screw is to move forward,it has to be rotated or turned clockwise.If the screw has to move backward it has to be rotated in anticlockwise
(or) Counterclockwise direction.
The relation between current and magnetic field is same as above.
The direction of current is same as, the way the tip of the screw moves(ie forward or backward movement). The direction of magnetic field is same as the direction of movement of head (clockwise or counterclockwise).