Ch:19 Electric circuits

What happens to the resistance of an LDR when the brightness of light falling on it increases?

• A Its resistance decreases.

• B Its resistance increases.

• C Its resistance increases then decreases.

• D Its resistance stays the same.

• A

• B

• C

• D

A student constructs four circuits, each containing a fuse. The fuse blows in one circuit and both lamps in the circuit go out. In which circuit does the fuse blow and both lamps go out?

• A

• B

• C

• D

The diagram shows a control circuit. The lamp is lit.The temperature of the surroundings increases. What will happen to the brightness of the lamp?

• A It will be brighter.

• B It will be less bright.

• C It will not change.

• D It will become brighter and then less bright

Which circuit contains a thermistor and a heater?

• A

• B

• C

• D

The diagram shows a relay being used to control a buzzer. What is the function of the circuit?

• A The buzzer switches off when the circuit becomes cold.

• B The buzzer switches off when the circuit becomes light.

• C The buzzer switches on when the circuit becomes cold.

• D The buzzer switches on when the circuit becomes light.

There is a 5A fuse in the circuit of an appliance. What is the purpose of the fuse and in which wire is it connected?

• A

• B

• C

• D

Identical resistors are connected together to form arrangements X, Y and Z.What is the correct order of the resistances of the arrangements from the largest to the smallest?

• A X → Y → Z

• B Y → X → Z

• C Z → X → Y

• D Z → Y → X

The circuit shows a wire WX connected to a cell. The potential difference (p.d.) between W and X is 1.5V. What is the reading on the voltmeter?

• A 0.4V

• B 0.6V

• C 0.9V

• D 4.0V

Which circuit shows a variable resistor used to control the brightness of a lamp?

• A

• B

• C

• D