Activity 12.3 Class 10 Science Electricity

Activity 12.3 Class 10 Science Electricity

Brief procedure:

Activity 12.3 asks us to check ammeter reading with nichrome wire of varying length.

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 crossectional area of the wire results in a decrease in the resistance. This results in an increase in the current flow.

Inference/conclusion: 

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.

Next: Resistance in series have the same current throughout the circuit: Activity 12.4.

See also: Experiment to demonstrate different materials offer different resistance: Activity 12.2.