Simple circuit：練習問題

Which of the following electrical components is used to measure the electric current flowing in a simple circuit?

A student wants to draw a circuit diagram for a component that can provide adjustable resistance. Which symbol should be used?

A wall socket is rated at \(240 \, \text{V}\) and protected by a \(13 \, \text{A}\) fuse. If a kettle (\(2200 \, \text{W}\)), a toaster (\(1000 \, \text{W}\)), and a television (\(150 \, \text{W}\)) are all plugged into this single socket and switched on simultaneously, what will happen?

What is the function of a switch in a simple electrical circuit?

A student performs an experiment with a uniform cylindrical metal wire that has an electrical resistance of \(12 \, \Omega\). The student carefully stretches the wire so that its length increases to three times its original value. Assuming the wire remains uniform and its total volume does not change during the stretching process, what will be the new electrical resistance of the wire?

What is the fundamental role of a cell (battery) in a simple electrical circuit?

If a light bulb does not light up when a switch in a simple circuit is closed, state two possible reasons for this observation, referring to the necessary conditions for a complete circuit.

You are given a cell, a switch, and two identical light bulbs. Draw a single labelled circuit diagram using standard symbols to show how these components can be connected such that if one bulb breaks, the other bulb will not light up. Explain why the other bulb fails to light up in this configuration.

A student is experimenting with a simple electrical circuit. They have a 1.5 V dry cell, a miniature light bulb, and several pieces of wire made of different materials: copper, plastic, and iron.

(a) To make the light bulb glow, which material should the student use for the connecting wires? Explain your choice by stating an important electrical property of that material.

(b) After successfully making the bulb glow, the student notices that if they deliberately create a gap in one of the connecting wires, the bulb immediately stops glowing. Explain, in terms of circuit conditions, why the bulb stops glowing.

A simple circuit is set up with a 9 V battery, a switch, and two resistors, \(R_1 = 3 \, \Omega\) and \(R_2 = 6 \, \Omega\).

(a) Draw a labelled circuit diagram showing \(R_1\) and \(R_2\) connected in series with the battery and switch. Use standard circuit symbols.

(b) Calculate the total resistance of the series circuit.

(c) If the current flowing through \(R_1\) in the series circuit is \(1 \, A\), calculate the voltage of the battery.

(d) Now, the two resistors, \(R_1\) and \(R_2\), are reconnected in parallel to a \(9 \, V\) battery, with the switch still controlling the entire circuit. Calculate the equivalent resistance of this parallel combination.

(e) Determine the current flowing through \(R_2\) in the parallel circuit.