Page 2 - HA

Activity---1

EXPERIMENT: To list the different factors affecting resistance.

Materials Required:

 Bulb

 Insulated copper wires/Nichrome wire

 1.5 V Battery
 Switches

Observation:

Ammeter (current) reading varies inversely with the change in length of the wire.

For example, if we double the length of the wire, the current reduces to half.

Ammeter reading changes with the change in the thickness of the wire. For
example, if we increase the cross-sectional area of a wire by double, its

resistance will be halved.

Explanation:
An increase in the length of the nichrome wire increases its resistance. This

increase in resistance is directly proportional to the length of the wire. As a result,

we see a proportionate decrease in the current flow.

As per Ohm’s law,

V=IR.

So, if the potential difference is kept constant,

I ∝ 1/R

i.e. I∝ 1/length of resistive wire.

Resistance is indirectly proportional to the cross-section area. An increase in the
cross sectional area of the wire results in a decrease in the resistance. This results in
an increase in the current flow.