Question 17
The diagram shows a
graph.
For a uniform metallic
wire, what could the graph not represent?
y-axis
x-axis
A current potential
difference
B resistance length
C resistance temperature
in °C
D potential
difference current
Reference: Past Exam Paper – November 2015 Paper 11 Q31
Solution:
Answer:
C.
A uniform metallic wire
obeys Ohm’s law (V = IR). So, a current-p.d. graph and a p.d.-current graph
would be straight line. [A and D incorrect]
Resistance of wire: R = ρL / A
So, a resistance-length
graph would also be a straight line. [B incorrect]
A graph of resistance
against temperature will not be a straight line as the resistance of the metal
wire increases with temperature. The higher the temperature, the greater the
increase in temperature. So, the graph would be a curve, not a straight line.
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