The statement below is followed by four options. Each option is related to the item in the statement, but only one is always true. Select the option that always holds and makes the statement true.
"A working electric circuit always has ______."
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A source of electric current
The answer must hold for every working electric circuit, without exception. An option that is present in most cases but can be missing in even one case is not always true.
Option (1) A source of electric current — current flows only when there is a source such as a cell, a battery or the mains supply; without a source no current flows and the circuit does not work, so this is always true.
Option (2) A switch — a cell joined to a bulb by two wires lights the bulb with no switch in the circuit.
Option (3) A bulb — a circuit can run an electric bell or a fan instead of a bulb.
Option (4) Copper wires — aluminium wires also carry current and are widely used.