IGCSEPhysics: Co-ordinated Sciences (Double Award)CIEExam Questions4. Electricity & MagnetismElectrical Quantities

Electrical Quantities (CIE IGCSE Physics: Co-ordinated Sciences (Double Award))

Exam Questions

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Electrical Quantities

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Electrical Quantities

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1a4 marks

A student sets up an electrical circuit. She draws part of the circuit diagram, as shown in Fig.8.1.

feb-march-2018-32-q8

On Fig.8.1, draw the circuit symbols for three devices so that the student can:

 
(i)
measure the total current in the circuit
[1]
 
(ii)
vary the current in the lamp B only
[1]
 
(iii)
measure the potential difference (p.d.) across lamp B.
[2]

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1b3 marks

The current in lamp A is 0.20 A. The potential difference (p.d.) across lamp A is 6.0 V.

Calculate the resistance of lamp A.

 

resistance = ......................................................Ω 

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2a
Sme Calculator3 marks

Fig. 10.1 shows a balloon hanging from an insulating thread.

q10a

(i)
A student gives the balloon a positive charge.
 
Which statement explains why the balloon becomes positively charged? Tick one box.
 
square The balloon gains electrons
square The balloon loses electrons
square The balloon gains protons
square The balloon loses protons

[1]

(ii)
The student brings a charged rod close to the balloon as shown in Fig. 10.2.
 
q10aii
State the type of charge on the rod.
 
Explain your answer. 
[2]

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2b1 mark

Electrical charges can move easily through some materials.

Draw a circle around each material that charges can move through easily.

copper plastic rubber silver wood

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3a4 marks

A student rubs a plastic rod with a dry cloth, as shown in Fig. 8.1. The rod becomes negatively charged.

rod
(i)
Use words from the box to complete the sentence.
air cloth electrons hand neutrons protons

  

The rod becomes negatively charged because ......................................... move from the ......................................... to the rod.

[2]

 

(ii)
The student moves the rod close to a suspended, charged rod. The two rods repel each other.
  
State the type of charge on the suspended rod.
[1]
 
(iii)
Explain your answer to (a)(ii).
[1]

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3b2 marks

A device has a metal case. Any charge on the case must be able to move to earth.

     
(i)
Draw one ring around a material that is suitable for the connection to earth.
     
copper glass plastic rubber
[1]
 
(ii)
Explain your answer to (b)(i).
[1]

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1a3 marks

A student rubs a polythene rod with a dry cloth. The polythene rod becomes negatively charged.

Describe and explain how the rod becomes negatively charged.

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1b2 marks

The negatively charged polythene rod hangs from a nylon thread so that it is free to turn.

 The student charges a second polythene rod and brings it close to the first rod, as shown in Fig.11.1.

feb-march-2018-32-q11
 

Describe and explain what happens when the negatively charged rods are close to each other.

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2a2 marks

A student experiments with electric charge.

The student uses a dry cloth to rub a plastic rod. The rod becomes positively charged.

Explain how the friction between the rod and the cloth causes the rod to become positively charged.

Use your ideas about the movement of charge.

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2b3 marks

The student suspends a balloon from an insulating thread, as shown in Fig. 9.1.

18p3-9b

The balloon has an electric charge.

Explain how the student can use a positively charged rod to determine the charge on the balloon.

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32 marks

The lamp of a car headlight is rated at 12 V, 50 W.

Calculate the current in the lamp when operating normally.

 

current = ......................................................... 

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4a1 mark

Fig. 9.1 shows the symbol for a 12V battery.

18p4-9a

Two lamps are connected in parallel with the battery.

 

On Fig. 9.1, using the correct symbols, complete the circuit diagram.

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4b3 marks

One of these lamps has a resistance of 6.0 Ω.

 
Calculate, for this lamp:

 
(i)
the current
 
 
current = ...........................................................[1]
 
(ii)
the power.
 
 
power = ...........................................................[2]

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4c3 marks

The power of the other lamp is 36 W.

 
Calculate the total energy delivered to this lamp in 20 hours.

 
 
energy = ...........................................................

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5a2 marks

Extended tier only

Fig. 9.1 shows current-potential difference graphs for a resistor and for a lamp.

feb-march-2018-42-q8

(i)
The potential difference (p.d.) applied to the resistor is increased. Tick the box that indicates the effect on the resistance of the resistor.
 

square resistance increases

square resistance is constant

square resistance decreases

 [1]
 
(ii)

The potential difference (p.d.) applied to the lamp is increased. Tick the box that indicates the effect on the resistance of the lamp.

   

square resistance increases

square resistance is constant

square resistance decreases

[1]

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5b2 marks

The p.d. across the lamp is 6.0V. Calculate the resistance of the lamp.

 

resistance = ......................................................... 

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5c2 marks

The lamp and the resistor are connected in parallel to a 6.0 V supply.

Calculate the current from the supply.

 

current = .........................................................

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5d2 marks

Extended tier only

The lamp and the resistor are connected in series to another power supply. The current in the circuit is 4.0 A.

Calculate the total p.d. across the lamp and the resistor.

 

 

p.d. = .........................................................

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6a1 mark

Fig. 10.1 shows a circuit used by a student to test a metal wire made of nichrome.

18-23-8a

State the name of component Z.

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6b1 mark

The current reading on ammeter X is 0.8 A. State the reading on ammeter Y.

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6c3 marks

The current in the nichrome wire is 0.8 A. The potential difference (p.d.) across the nichrome wire is 4.5 V.

Calculate the resistance of the nichrome wire.

 
 
resistance = ..................................................... Ω 

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6d2 marks

Extended Tier Only

The student tests a different nichrome wire, which is thicker than the wire in (c), but of the same length. When testing this wire, the current in the wire is different from the value given in (c).

State and explain the difference in current.

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7a5 marks

Fig. 10.1 shows an electrical circuit.

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(i)
State the name for the component labelled X and state its function in this circuit.
[2]
 
(ii)

Describe how the circuit shown in Fig. 10.1 could be used to find the resistance of the fixed resistor R.

[3]

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7b4 marks

An electrical heater has a resistance of 21.8 Ω when connected to a 240 V mains supply.

 
(i)

Calculate the current in the heater.

 

 

current = ....................................................... A [3]

(ii)

Suggest a rating for the fuse to be fitted to the mains plug for the heater.

 

fuse rating = ....................................................... A [1]

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8a4 marks

An uncharged conducting metal plate rests on insulating supports. Fig. 10.1 shows the plate and a positively charged insulating plastic sheet placed on top of the metal plate.

IAtK5JmP_q10a

(i)

Describe any flow of charge that takes place when the plastic sheet is placed onto the metal plate.

[1]

(ii)

On Fig. 10.1, draw how charges are now arranged within the metal plate.

[1]

(iii)

State and explain if this arrangement of charge helps to keep the plastic sheet in place.

[2]

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8b2 marks

Fig. 10.2 shows two uncharged conducting spheres suspended on insulating threads.

O1Q~0~0N_q10b
1.

The spheres are now both given positive charges. On Fig. 10.2, draw a possible position of each sphere and thread.

2.

Explain the positions you have drawn.

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1a1 mark

Extended Tier Only

State, in terms of their structure, why metals are good conductors of electricity.

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1b4 marks

Extended tier only

A cylindrical metal wire W1, of length L and cross-sectional area A, has a resistance of 16 Ω.

A second cylindrical wire W2, of length L over 2 and cross-sectional area 2A, is made from the same metal.

Determine

(i)

the resistance of W2,

 

 

resistance of W2 = ...........................................................[2]

(ii)

the effective resistance of W1 and W2 when connected in parallel

 

 

resistance of parallel pair = ...........................................................[2]

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2a4 marks
(i)
Fig. 8.1 shows a positively charged cube of insulating material. The cube is fixed to a piece of wood that is floating on water. A negatively charged rod is held above the piece of wood and brought close to the cube, as shown.
 
q8i
State and explain any movement of the piece of wood.
[2]
 
(ii)
Fig. 8.2 shows two cubes of insulating material. One is positively charged and the other is negatively charged. The cubes are fixed to a piece of wood that is floating on water. Charged rods are held above the piece of wood and brought close to the cubes, as shown.
 
q8ii
State and explain any movement of the piece of wood. 
[2]

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2b2 marks

Extended Tier Only

In terms of a simple electron model, describe the differences between conductors and insulators.

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3a2 marks

Extended tier only

(i)
Describe what is meant by an electric field.
[1]
(ii)
State what is meant by the direction of an electric field.
[1]

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3b4 marks

Fig. 8.1 shows a polystyrene ball covered with aluminium paint. The polystyrene ball is suspended between two charged metal plates by an insulated thread.

q8

The ball oscillates between the two charged plates.

Explain why the ball oscillates.

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3c3 marks

Extended tier only

There is a current of 0.29 A in an electrical circuit.

Calculate the time taken for a charge of 15 C to flow through the electrical circuit.

 

 

time = .........................................................

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4a4 marks

Extended tier only

A light-emitting diode (LED) is a diode that emits light when there is a current in it.

Draw a circuit diagram showing an LED, connected so that it is lit, in series with a battery and a fixed resistor. Use standard electrical symbols.

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4b2 marks

The p.d. across the LED when lit is 3.1 V and the current in the LED is 0.030 A.

Calculate the value of the resistance of the LED when lit.

 

 

resistance = .........................................................

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4c4 marks

Fig. 8.1 shows a power supply of e.m.f. 10.5 V connected in series with a lamp and a heater.

The p.d. across the lamp is 2.1 V and the current in the lamp is 1.5 A.

may-june-2020-42-q8

Calculate:

(i)

the resistance of the heater

 
 

resistance = ......................................................... [2]

(ii)

the power of the heater.

 
 

power = ......................................................... [2]

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