Electric circuits：練習題

A circuit consists of a battery and three identical lamps connected in series. What happens to the other two lamps if the filament of one lamp breaks?

A potential divider circuit consists of a negative temperature coefficient (NTC) thermistor and a fixed resistor connected in series with a constant voltage power supply. A voltmeter is connected across the fixed resistor.

What happens to the resistance of the thermistor and the reading on the voltmeter when the temperature of the thermistor decreases?

In the circuit shown, a \(24\text{ V}\) power supply is connected to two parallel branches. Branch A contains a single \(12\text{ }\Omega\) resistor. Branch B contains two \(4.0\text{ }\Omega\) resistors in series with each other. Calculate the total current provided by the power supply.

In a series circuit containing a battery and three different resistors, what is the relationship between the current at different points in the circuit?

A \(9.0\text{ V}\) battery is connected in series with a \(10\text{ }\Omega\) resistor and a \(20\text{ }\Omega\) resistor. What is the potential difference across the \(20\text{ }\Omega\) resistor?

State how the resistance of a thermistor changes when the temperature of its surroundings increases.

A \(12\text{ V}\) battery is connected to a potential divider consisting of a variable resistor and a fixed \(4.0\text{ k}\Omega\) resistor. Determine the resistance required for the variable resistor so that the output potential difference across the fixed resistor is exactly \(3.0\text{ V}\).

A potential divider uses an LDR in series with a fixed resistor. Explain the change in output voltage across the fixed resistor when the light intensity on the LDR increases, referring to the resistance changes involved.

A \( 12\text{ V} \) power supply is connected to two resistors, A and B, which are connected in parallel with each other. Resistor A has a resistance of \( 4.0\text{ }\Omega \) and resistor B has a resistance of \( 6.0\text{ }\Omega \).

(a) State the value of the potential difference (p.d.) across resistor B. (1)
(b) Calculate the current passing through resistor A. (2)
(c) Determine the total current provided by the power supply to the parallel arrangement. (2)

A circuit consists of a \(12 \text{ V}\) power supply connected to a parallel combination of two resistors, \(R_1 = 6.0 \Omega\) and \(R_2 = 12.0 \Omega\). This parallel combination is connected in series with a third resistor, \(R_3 = 4.0 \Omega\).

(a) Draw a circuit diagram for this arrangement.

(b) Calculate the combined resistance of the parallel combination of \(R_1\) and \(R_2\).

(c) Determine the total resistance of the entire circuit.

(d) Calculate the total current flowing from the power supply.

(e) Determine the potential difference across resistor \(R_3\).

(f) Calculate the total electrical energy consumed by the circuit in \(5 \text{ minutes}\).