6091 Physics Chapter 18 DC Circuits

In the circuit shown, the cells and ammeters all have negligible resistance. What are the readings on the ammeters A1, A2 and A3?

• A1 = 2, A2 = 1, A3 = 2
• A1 = 2, A2 = 1, A3 = 4
• A1 = 4, A2 = 2, A3 = 2
• A1 = 4, A2 = 2, A3 = 4

Answer explanation

Explanation for the answer (optional)

In the circuit shown, R is a light-dependent resistor. Its resistance decreases when the intensity of the light shining on it increases. What effect does an increase of light intensity on R have on the brightness of the two lamps L1 and L2?

• L1 decreases, L2 decreases
• L1 decreases, L2 increases
• L1 stay the same, L2 decreases
• L1 stays the same, L2 increases

The diagram shows a thermistor connected in a potential divider circuit. The resistance of the thermistor decreases when its temperature rises. The thermistor is heated. What happens to the potential difference across the thermistor as it is heated?

• It decreases, but not to zero.
• It decreases to zero.
• It increases, but not to 6V
• It increases to 6V

The diagram shows six identical lamps, four ammeters and a battery. The current in the battery is 1.5 A. Which ammeter reads 1.0 A?

• A
• B
• C
• D

In the circuit shown, the ammeter reading is 3 A. What is the ammeter reading when a resistor of 2000 ohms is connected in parallel with the 2 ohm resistor?

• slightly less than 3 mA
• slightly more than 3 mA
• slightly less than 3 A
• slightly more than 3 A

A variable potential divider has a sliding contact S that can be moved between end P and end Q of a 10 ohm resistor. The potential divider is connected to a constant 6 V power supply and another 10 ohm resistor, as shown below. What happens to the potential difference between X and Y as S moves from P to Q?

• It decreases from 6 V to 0 V.
• It decreases from 3 V to 0 V
• It decreases from 6 V to 3 V.
• It increases from 0 V to 3 V.

The diagram shows a circuit containing a thermistor. The resistance of the thermistor decreases as its temperature increases. Which graph shows how the ammeter reading changes as the temperature of the thermistor rises?

• A
• B
• C
• D

The diagram shows a circuit. When the switch is closed, what happens to the readings of voltmeters V1 and V2 ?

• V1 decreases, V2 decreases
• V1 decreases, V2 increases
• V1 increases, V2 decreases
• V1 increases, V2 increases

The circuit diagram shows a 1.0 ohm resistor in series with a parallel arrangement of a 1.0 ohm resistor and a 2.5 ohm resistor. The currents in the two parallel resistors are shown. What is the reading on the voltmeter?

• 7.0 V
• 10 V
• 12 V
• 17 V

A resistor and a light-dependent resistor (LDR) are connected in series with a battery, as shown. When very bright light is shone on the LDR, the readings on both the ammeter and the voltmeter change. How do they change?

• reading on ammeter decreases, reading on voltmeter decreases.
• reading on ammeter decreases, reading on voltmeter increases.
• reading on ammeter increases, reading on voltmeter decreases.
• reading on ammeter increases, reading on voltmeter increases.