Answer: B. A switch is closed.
Current flows in the circuit when a switch is closed.
Current is flow of charge through an element. when we apply a voltage (or) a battery to element. electrons move from negative terminal to positive terminal, while transferring the energy from battery (or) voltage source to the element. If we assume a battery of EMF ‘E” is connected across an element through a switch “S” as shown in below figure.
For electrons to flow from negative terminal to positive terminals the entire circuit should be closed. That means there should not be any gaps in the circuit, so current flows in the circuit when switch is closed.
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