Question

According to Ohm’s law the graph of potential difference and current is _ _ _ _ _ _ _ .
A. Straight line passing through origin
B. Curved
C. Line having an intercept on x-axis
D. Circular

Answer 1

Hint: Ohm’s law states that the current flowing through a conductor is directly proportional to the potential difference across the conductor. The relation between potential difference (V) and the current (i) through the conductor is V = iR, where R is the resistance of the conductor.

Complete step-by-step answer:
According to Ohm’s law, the current flowing through a conductor is directly proportional to the potential difference across the conductor.
Suppose the ends of a conductor are connected with the terminals of a variable source of e.m.f V. The meaning of e.m.f V is that the cells will create a potential difference of V across the ends of the conductor. Due to this potential difference there is flow of electrons in the circuit. This flow of charges (electrons) in one unit of time is called current.
Suppose we are using an ammeter to measure the current (i) flowing through the conductor.
Since the source of e.m.f is variable, we can measure the current through the conductor for different values of potential difference across the conductor.
When we do this experiment it is found that the current through the conductor is directly proportional to the potential difference across the conductor.
i.e. V $\alpha $ i.
It is also found that V = Ri, where R is the resistance of the conductor. In this case, R is also a proportionality constant.
V = iR is an equation of a straight line passing through origin.
Hence, the correct option is A.

Note: The above statement is true only at a constant temperature. As the temperature of a conductor changes its resistance also changes. Therefore, the graph of potential difference and current will not be a straight line because the value of resistance R is not constant.