I have a very fundamental question, will an electric bulb glow with one point connected to the positive terminal of the electric line and the other point to earth? In my school some 10 years back I learnt that we are connecting the two points of the bulb to positive and negative to make the connection closed.
As earth is considered as a huge potential of ions it could be considered as the negative side. If my thinking is wrong then why do the LEDs glow in the tester? In the tester we touch the tail which is indirectly connected to earth.
Note I dont know what the tester is called in other countries. The Tester is a small instrument to check if the current flows in a circuit or not and is size of a pen.
Best Answer
Yes and no.
Yes, because the earth cable is connected to the neutral at some point. In some country this is done at the entry point of every buildings, in other it's earlier. Thus the circuit will be closed and the bulb will light up.
No, because in nowadays house, residual current circuit-breakers are used. If the return current is flowing through the earth cable and not through the neutral cable (>20mA typically) the breaker will break and your bulb won't work.
About your tester: The human body that touches a terminal of the light included into your tester acts as a capacitor. This is called "Body capacitance". Because the other terminal is connected to an AC source (the main), a current (very very small) flows through the tester and it lights up.