O level D.C. Circuits (10 qns)

A circuit is set up in the diagram.

What is the ammeter reading in the circuit?

• 0.50A

• 0.67A

• 1.5A

• 2.0A

Three resistors are connected in a circuit as shown.

What is the reading on the voltmeter?

• 10V

• 12V

• 15V

• 17V

What will happen to the readings on the voltmeter and ammeter when switch S is closed?

• Voltmeter reading Increases

• Voltmeter reading Decreases

• Ammeter reading Increases

• Ammeter reading Increases

The diagram shows a potential divider circuit with a light-dependent resistor (LDR) and a fixed resistor.

Which conditions will give a high output potential difference?

• light shining on the LDR:

  bright

• light shining on the LDR:

  dim

• the p.d. across fixed resistor:

  high

• the p.d. across fixed resistor:

  low

The lamps H are controlled by switch X. The lamp F is controlled by switch Y, but only comes on if lemps H are also switched on. Lamps H and F have a normal working voltage of 12V

Which circuit would allow all the lamps to work as above at normal brightness?

• 
• 
• 
• 

What is current I?

• 5.4 mA

• 11 mA

• 21 mA

• 43 mA

In the diagram below, the potential difference across the battery is denoted by Vℰ, and the potential difference across R2 is denoted as V-out.

What is the ratio of Vℰ : V-out?

• R1 : R2

• R2 : (R1+R2)

• (R1+R2) : R1

• (R1+R2) : R2

What happen to the brightness of the lamps as the contact X moves from Q to P?

• lamp 1:

  dimmer

• lamp 1:

  brighter

• lamp 2: dimmer

• lamp 2:

  brighter

An electrical component is to be placed in the circuit at Z, to allow the brightness of the lamp to be varied from bright to dim as the temperature changes.

What should be connected at Z?

• 
• 
• 
• 

The diagram shows a simple circuit consisting of three identical bulbs and a variable resistor. The e.m.f. of the battery is 3.0V.

When the variable resistor is adjusted to 0Ω, the current through the battery is 0.50A. What is the resistance of each bulb?

• 2.0Ω

• 4.0Ω

• 6.0Ω

• 18.0Ω