Revision NotesExam Questions
IGCSEPhysics: Co-ordinated Sciences (Double Award)CIEExam Questions4. Electricity & MagnetismElectric Circuits & Electrical Safety

Electric Circuits & Electrical Safety (CIE IGCSE Physics: Co-ordinated Sciences (Double Award))

Exam Questions

3 hours34 questions

Select a question set to download for
Electric Circuits & Electrical Safety

Select an answer set to view for
Electric Circuits & Electrical Safety

17 marks

A student investigates a wind turbine, which is an electrical generator driven by a propeller blade.

Plan an experiment which will enable him to investigate how the current in a resistor connected across the terminals of the turbine varies with the speed of the air flow through the turbine.

The apparatus available includes:

a model wind turbine as shown in Fig. 4.1

an electric fan to provide the moving air to turn the turbine

a device for measuring air speed.

In your plan, you should:

  • list any additional apparatus needed
  • complete the wind turbine circuit diagram on Fig. 4.1
  • state the key variables to be kept constant
  • explain briefly how to carry out the experiment, including how the speed of the air flow is to be changed
  • explain how to use the readings to reach a conclusion.

6sSLF4yz_q4

How did you do?

Did this page help you?

2a4 marks

A student determines the resistances of some filament lamps.

Fig. 2.1 shows the first circuit she uses. 

p6-circuit

(i)
Record the potential difference V subscript 1 across the lamp L1, as shown on the voltmeter in Fig. 2.2.
p6-meters
                                     
V subscript 1 = .................................................. V [1]

(ii)
Record the current I subscript 1 in the circuit, as shown in Fig. 2.3.
    
    
I subscript 1 = .................................................. A [1]
      
     
(iii)
Calculate the resistance R subscript 1 of the filament of lamp L1. Use the equation R subscript 1 equals V subscript 1 over I subscript 1 . Include the unit.
                           

R subscript 1 = ..................................................... [2]

How did you do?

2b1 mark

The student disconnects the voltmeter. She connects lamp L2 in series with lamp L1. She connects the voltmeter across lamp L2.

        
She measures the current I subscript 2 in the circuit and the potential difference V subscript 2 across lamp L2.

         
I subscript 2 = ..... 0.30 A .....
V subscript 2 = ..... 1.7 V .....


Calculate the resistance R2 of the filament of lamp L2. Use the equation R subscript 2 equals V subscript 2 over I subscript 2.

R subscript 2 = .............................................


The student disconnects the voltmeter. She connects lamp L3 in series with lamps L1 and L2. She connects the voltmeter across lamp L3.


She measures the current I subscript 3 in the circuit and the potential difference V subscript 3 across lamp L3.            

I subscript 2 = ..... 0.26 A .....
V subscript 2 = ..... 1.2 V .....
     

Calculate the resistance R3 of the filament of lamp L3. Use the equation R subscript 3 equals V subscript 3 over I subscript 3.

R subscript 3 = ...................................

How did you do?

2c1 mark

Calculate R1 + R2 + R3. Give your answer to a suitable number of significant figures for this experiment.

    
   
R1 + R2 + R3 = ..................................................... 

How did you do?

2d2 marks

Some students make suggestions about the results of the experiment.

Suggestion A:  R1 + R2 + R3 should be equal to 3 × R1

Suggestion B:  R1 + R2 + R3 should be less than 3 × R1

Suggestion C:  R1 + R2 + R3 should be greater than 3 × R1

State which suggestion A, B or C agrees with your results. Justify your answer by reference to your results.

How did you do?

2e3 marks

Draw a circuit diagram to show the circuit used in part (b) with all three lamps connected in series.

How did you do?

Did this page help you?

3a1 mark

A student is investigating a circuit containing different lamps.
She is using the circuit shown in Fig. 3.1.

atp-4

On Fig. 3.1, draw a voltmeter connected so that it measures the potential difference (p.d.) across lamp X.

How did you do?

3b1 mark

The student uses the ammeter to measure the current in the circuit.

 
atp-5
 

Record the current IS in the circuit, as shown in Fig. 3.2.

IS = ............................................................

How did you do?

3c4 marks
(i)
The student uses the voltmeter to measure the p.d. VX across lamp X and then reconnects the voltmeter to measure the p.d. VY across lamp Y.
 
atp-6
 

Record the value of the p.d. VX  across lamp X, shown in Fig. 3.3.

VX  = ...............................................................

Record the value of the p.d. VY across lamp Y, shown in Fig. 3.4.

VY  = ...............................................................
[1]

(ii)
She then measures the p.d. VS across both lamps in series.
 
atp-7
 
Record the value of the p.d. VS across both lamps in series, shown in Fig. 3.5.
 
VS  = ...............................................................[1]
(iii)

A student suggests that VS should be equal to (VX + VY).
State whether the readings support this suggestion. Justify your statement with reference to the results.

[2]

How did you do?

3d1 mark

Calculate the resistance R1 of lamp X. Use the readings from (b) and (c)(i) and the equation

R subscript 1 space equals space V subscript X over I subscript S.
 
 
R1 = ......................................................Ω 
 
.

How did you do?

3e4 marks

Extended tier only

(i)

The circuit components are to be rearranged so that

  • lamps X and Y are connected in parallel
  • the ammeter measures the current in lamp X only
  • the voltmeter measures the p.d. across the lamps.

Draw a circuit diagram of this arrangement.

[2]

(ii)
The student sets up the circuit as described in (e)(i).
 
She measures and records the current in lamp X and the p.d. across the lamps.
 
She then calculates a new resistance R2 for lamp X in this parallel circuit.
 
R2 = 8.3 Ω

 

The student notices that lamp X is very bright in this parallel circuit, but it was dim in the series circuit in (a).

Suggest how temperature affects the resistance of a lamp.
Justify your suggestion by reference to the value of R1 from (d) and the value of R2.

[2]

How did you do?

Did this page help you?