A student studies the behaviour of a nichrome wire by gradually increasing the…
PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity
Problem
A student studies the behaviour of a nichrome wire by gradually increasing the potential difference across it at room temperature. She records the following readings:
Potential difference V (V): 1.0, 2.0, 3.0, 4.0, 5.0
Current I (A): 0.10, 0.20, 0.28, 0.34, 0.38
Answer the following:
(i) Draw a suitable graph using the above data, taking current along the vertical axis and potential difference along the horizontal axis.
(ii) From the shape of the graph, identify the range of voltages, if any, over which the wire approximately obeys Ohm’s law.
(iii) Explain physically why the graph ceases to be a straight line at higher voltages.
(iv) How does the resistance of the wire change as the potential difference increases? Give reasons based on the graph.