CBSE Class 10 Science 2015 Term I Set 2

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Question : 22
Total: 36
State Ohm's law. Draw a labelled circuit diagram to verify this law in the laboratory. If you draw a graph between the potential difference and current flowing through a metallic conductor, what kind of curve will you get ? Explain how would you use this graph to determine the resistance of the conductor
Solution:  
Ohm's law states that the electric current flowing through a conductor is directly proportional to the potential difference across its two ends, when other physical conditions like temperature etc., remain constant.
i.e., or
VI
V
I
= Constant
=R

V=IR
or
Thus, the ratio V:I is a constant. This constant is called the resistance (R) of the conductor. Circuit diagram for Ohm's law :
If a graph is drawn between the potential difference (V) and current (I), the graph is found to be a straight line passing through the origin. This shows that the current is directly proportional to the potential difference. Thus, the ratio
V
I
remains constant. This constant is called the resistance of the conductor. The gradient of the straight line graph is related to the resistance (R) of the conductor.
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