A homeowner installs two identical electric heaters, each of resistance R, on separate branches of a household circuit that is supplied by an ideal 120 V source. Both heaters have individual ON/OFF switches. Initially only heater A is ON; heater B is OFF.
Assume the wiring resistance is negligible.
(a) Describe qualitatively how the equivalent resistance of the circuit seen by the source changes when heater B is switched ON.
(b) Predict and justify how the total current drawn from the 120 V source changes when heater B is turned ON.
(c) After heater B is switched ON, compare the power output (and therefore the heating rate) of heater A to its value before heater B was turned ON. Explain your reasoning.
(d) Some household circuits include a fuse or circuit breaker. Explain qualitatively why adding additional parallel appliances can cause such protective devices to trip, making explicit reference to your answers above.