Describe a simple experiment to differentiate good conductors from bad conductors.

Sanjiv took a dry cell and connected to its central terminal to a copper wire, such that another end of the copper wire is free. The base of the cell was connected to another copper wire, whose other end is connected to a terminal of a flashlight bulb. The other terminal of the flashlight bulb is connected to another copper wire with a free end. The free ends of the copper wires he connected to materials such as a silver spoon, a brass candle stand, a steel plate, a plastic plate, an eraser, a rubber balloon, etc. He noticed that in the case of the first three materials the bulb glowed. However, in the case of the next three materials bulb did not glow. He wanted to know the reason behind it, so he contacted his friend Samir. Samir explained such things on the basis of characteristics of conductor and insulator.
Answer the following questions based on the above information:
$\left(i\right)$ What are the values displayed by Samir?

Sanjiv took a dry cell and connected to its central terminal to a copper wire, such that another end of the copper wire is free. The base of the cell was connected to another copper wire, whose other end is connected to a terminal of a flashlight bulb. The other terminal of the flashlight bulb is connected to another copper wire with a free end. The free ends of the copper wires he connected to materials such as silver spoon, a brass candle stand, a steel plate, a plastic plate, an eraser, a rubber balloon, etc. He noticed that in the case of the first three materials the bulb glowed. However, in the case of the next three materials bulb did not glow. He wanted to know the reason behind it, so he contacted his friend Samir. Samir explained such things on the basis of characteristics of conductor and insulator.
Answer the following questions based on the above information :

$\left(ii\right)$ What role do the above materials play in an electric circuit?