Question

What conclusion can you draw from the following observations on a resistor made of alloy manganin? Current Voltage Current Voltage A V A V 0.2 3.94 3.0 59.2 0.4 7.87 4.0 78.8 0.6 11.8 5.0 98.6 0.8 15.7 6.0 118.5 1.0 19.7 7.0 138.2 2.0 39.4 8.0 158.0

Answer 1

From the given data, calculate the resistance of resistor at different values of current and voltage.

Current (A)	Voltage (V)	Resistance (ohm)
0.2	3.94	19.70
0.4	7.87	19.68
0.6	11.8	19.67
0.8	15.7	19.63
1	19.7	19.70
2	39.4	19.70
3	59.2	19.73
4	78.8	19.70
5	98.6	19.72
6	118.5	19.75
7	138.2	19.74
8	158	19.75

It is clear from the above observations that the current in the resistor is proportional to the current. It means it follws the Ohm’s law.

V∝I V I =R

The ratio of the voltage and the current gives the resistance of the conductor.

Thus, the manganin is an Ohmic conductor and the resistance of the resistor is 19.70 Ω.