Activity 12.3 Class 10 Science Electricity
Activity 12.3 asks us to check ammeter reading with nichrome wire of varying length.
- 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.
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,
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 crossectional area of the wire results in a decrease in the resistance. This results in an increase in the current flow.
This experiment relates to the length of the wire and the cross-sectional area with the resistance. It proves if we increase the length of an object or decrease its cross-sectional area, its resistance will also increase proportionally.