電流、電位差與電阻：練習題

Which equation correctly links charge flow (\(Q\)), current (\(I\)), and time (\(t\))?

How does the resistance of a filament lamp change as the temperature of the filament increases?

A total of \(300\text{ C}\) of charge flows through a component when a potential difference of \(12\text{ V}\) is applied. How much energy is transferred?

Which of the following circuit symbols correctly represents a thermistor?

A heater is connected to a \(230\text{ V}\) mains supply. If the current through the heater is \(8\text{ A}\), calculate the power of the heater.

A resistor has a resistance of \( 20\ \Omega \). Calculate the potential difference required to move a current of \( 0.2\ \text{A} \) through it.

Explain how the resistance of a Light Dependent Resistor (LDR) is affected when it is moved from a bright room into a dark cupboard.

The provided graph shows the I-V characteristic of a filament lamp. Explain, in terms of particles, why the resistance increases at higher potential differences.

A student builds a simple circuit containing a battery and a single fixed resistor with a resistance of \( 15\ \Omega \).

a) Name the circuit component that should be connected in series with the resistor to measure the current.
b) When the circuit is closed, the potential difference across the resistor is \( 6.0\ \text{V} \). Calculate the current flowing through the resistor. Use the equation: \( V = I \times R \).

Filament lamps are examples of non-ohmic components. A student sets up a circuit to investigate the I-V characteristic of a filament lamp.

a) Describe how the student should connect an ammeter and a voltmeter to the lamp to measure the necessary values.
b) Explain why the resistance of the filament lamp increases as the temperature of the filament increases. Use the concept of particles in your answer.
c) Sketch the expected I-V characteristic graph for the filament lamp, showing both positive and negative values of potential difference.