What is an electric circuit?
The conducting path through which electricity flows is called electric circuit.
Electric Circuit consists a source of electric current (i.e. cell), a key and a bulb(electric device). They are properly connected through conducting wires. These conducting wires provide a continuous path for the flow of electricity. Then the key is closed, the bulb glows, showing that electricity flows in the circuit. If the key is opened, the bulb doesn't glow and hence no electricity flows in the circuit.
When the switch is off, the bulb doesn't glow, because there is a break or disconnection in the circuit. Such a circuit, in which there is a break or disconnection is called open circuit.
when the switch is on, the bulb glows. There is no gap or disconnection in the circuit. Such circuit in which there is discontinuity is called a closed circuit.