What is the function of an electromagnet in an electric doorbell?
it acts as a switch to open the circuit.
it acts as a switch to close the circuit.
it repels a metal striker, which then pulls away from the bell.
it attracts a metal striker, which then hits the bell.

The correct answer is option - its attracts a metal striker which then hits the bell.

Explanation:

The mechanism of the doorbell is very simple whenever someone presses the doorbell switch it completes the electric circuit that allows the electric current to flow through the electromagnet present in the doorbell.

The current that flows through the electromagnet is then attracts the striker of the bell that hits the bell and the bell makes the sound. Doorbells are the device that works on low voltage.

Thus, the correct answer is - it attracts a metal striker which then hits the bell.

these are the main green house gases

CO2 ,SO2,NO and CH4