Question

We did a lab studying resistance and Ohm’s Law. In my lab, my light bulb circuit element did not obey Ohm’s law b/c my data did not convey a proportional relationship between voltage drop and current. How do I answer:

If either or both of your circuit elements did not obey Ohm’s Law, can you think of any reasons for the non-ohmic behavior? In other words what might be happening to one or both of the elements as the applied voltage drop increases?

Answer 1

Both the bulb follows the non-ohmic behaviour as its voltage-current graph does not follow a straight line (as obtained by the experimental data). Instead, it must be giving a curve with an increasing gradient. It shows that the resistance increases as the current increases.

As the voltage across a non-ohmic conductor such as a bulb increases, the electrons that are leading to the flow of current, carry more energy. When they collide with metal atoms in the conductor, they transfer more energy. This makes the atoms vibrate more and more. This increases the resistance and the temperature and causes the non-linear or non-ohmic behaviour.