Household electricity ：練習問題

Which of the following units is most commonly used by electricity companies to measure energy consumption for calculating a household’s monthly electricity bill?

In the parallel circuit shown in the diagram, there are three identical light bulbs. If bulb L2 burns out (its filament breaks), what will happen to bulbs L1 and L3?

A faulty electric iron has a damaged internal live wire that is touching its metal casing. If the Earth wire in the plug is broken or missing, what is the most likely consequence if a person touches the casing?

Which of the following energy conversions is the primary process occurring in an electric doorbell when it is pressed?

In a standard household 3-pin plug, which of the following is the primary function of the Earth wire (typically colored yellow/green or green)?

Identify the scientific instrument used in a laboratory to directly measure the electrical energy transferred to an appliance over time.

A desk lamp draws a current of \(0.5 \, A\) when connected to a standard \(220 \, V\) mains supply. Calculate the power rating of the lamp in watts (\(W\)).

Explain why using a multi-way adaptor to connect several high-power appliances to a single wall socket increases the risk of an electrical fire.

Household electrical appliances are almost always connected in parallel circuits rather than series circuits.

(a) If three identical light bulbs are connected in parallel to the mains supply, what can be said about the voltage across each bulb compared to the mains voltage?

(b) State two advantages of using parallel circuits for household lighting instead of series circuits.

(a) Explain why household electrical appliances are typically connected in parallel circuits rather than series circuits. Give two reasons.

(b) Fuses and circuit breakers are important safety devices in household electricity. Briefly explain the function of a fuse in protecting electrical circuits and appliances.

(c) An electric fan in a household operates at $$240 \, V$$ and has a resistance of $$160 \, \Omega$$. Calculate the current drawn by the fan when it is operating.