CIE iGCSE Co-Ordinated Science P4.2.2 Electric current Exam Style Questions Paper 3
Question
(a) Complete the following sentences using the words shown. Each term may be used once, more than once or not at all. current ohms charge newtons resistance volts
A flow of electrons is called a …………………………. .
Electromotive force (e.m.f.) is measured in …………………………. .
To calculate the resistance of a component you divide the voltage by the ……………………….. .
(b) Energy transfers occur when electrical energy is supplied to a lamp. Fig. 12.1 shows a lamp
and the energy transfers.
Use information from Fig. 12.1 to calculate the wasted energy.
wasted energy = ……………………………………………… J
(c) Fig. 12.2 shows a ray of light from the lamp entering a glass block.
(i) On Fig. 12.2 continue the path of the ray into the block as it is refracted.
(ii) On Fig. 12.2 label the angle of incidence with an i and the angle of refraction with an r.
(d) Fig. 12.3 represents a visible light wave.
(i) On Fig. 12.3 use a double-headed arrow (↔ or ↕) and the letter W to show one wavelength.
(ii) On Fig. 12.3 use a double-headed arrow (↔ or ↕) and the letter A to show the amplitude of the wave.
▶Answer/Explanation
Ans:
12(a) current ;
volts ;
current ;
12(b) 360 (J );
12(c)(i) ray drawn correctly ;
12(c)(ii) i and r labelled correctly ;
12(d)(i) one wavelength correctly shown ;
12(d)(ii) amplitude correctly shown ;
Question
Fig. 9.1 shows a washing machine.
(a) (i) The washing machine uses:
• a heater to heat the water
• a motor to pump the hot water through the machine.
The motor and the heater are connected in a parallel circuit.
The motor and the heater are each operated by separate switches.
The circuit symbol for a heater is 
The circuit symbol for a motor is 
Fig. 9.2 shows an incomplete circuit diagram for the washing machine.
Complete the circuit diagram on Fig. 9.2.
(ii) The resistance of the heater is 20 Ω.
The resistance of the motor is 80 Ω.
Identify from the list the most likely value for the combined resistance of the heater and
motor connected in parallel.
Explain your answer.
16 Ω 20 Ω 50 Ω 80 Ω 100 Ω
combined resistance = …………………………. Ω
explanation …………………………………………………………………………………………………………
(iii) The current in the wires of the electrical circuit is a flow of charged particles.
State the name of the particles that flow in the wires of the electrical circuit.
(iv) The current-carrying coil in the motor experiences a turning effect.
This turning effect can be increased by increasing the number of turns on the coil.
State two other ways to increase this turning effect.
1 …………………………………………………………………………
2 …………………………………………………………………………
(b) Inside the washing machine, some of the water evaporates.
During evaporation, water changes state from a liquid to a gas.
(i) Complete the diagrams in Fig. 9.3 to show the arrangement and separation of molecules
in a liquid and in a gas.
(ii) During evaporation, the water does not boil.
State the boiling point of water.
…………………………………………….. °C
▶️Answer/Explanation
Ans : 9(a)(i) all symbols correct ;
heater and motor in parallel connection ;
switches correctly placed ;
9(a)(ii) 16 (Ω) ;
combined resistance in parallel is less than either individual resistance ;
9(a)(iii) electrons ;
9(a)(iv) increase current ;
increase strength of magnetic field ;
9(b)(i) liquid – all molecules touching random arrangement ;
gas – molecules widely separated (no more than seven shown) and random arrangement ;
9(b)(ii) 100 (°C) ;
Question
(a) Table 6.1 shows the audible frequency range of five animals.
(i) State which animal in Table 6.1 can hear a sound with the highest pitch.
(ii) State which animal in Table 6.1 has the smallest audible frequency range.
(iii) State the audible frequency range for a human.
from …………………………………. Hz to …………………………………. Hz
(b) The volume of an elephant is 3.4 m3.
The average density of the elephant is 1030 kg / m3.
Calculate the mass of the elephant.
mass = ……………………………………………. kg
(c) The elephant sprays its skin with water and leaves the water to evaporate.
(i) Describe the process of evaporation in terms of water molecules.
(ii) Suggest why the elephant sprays its skin with water and leaves the water to evaporate.
(iii) During evaporation, liquid water changes state and becomes water vapour, a gas.
Complete the diagrams in Fig. 6.1 to show the arrangement of molecules in liquid water and in water vapour.
▶️Answer/Explanation
Ans : 6(a)(i) bat ;
6(a)(ii) elephant ;
6(a)(iii) 20 (Hz) to 20 000 (Hz) ;
6(b) mass = density × volume (in any form) or 1030 × 3.4 ;
= 3500 (kg) ;
6(c)(i) fastest moving molecules escape ;
from the surface of the liquid ;
6(c)(ii) evaporation has a cooling effect ;
6(c)(iii) liquid – all molecules touching random arrangement ;
gas – molecules widely separated (no more than seven shown) and random arrangement ;
Question
(a) A torch (flashlight) contains a cell, a switch, and a lamp connected in series.
(i) Complete the circuit diagram in Fig. 6.1. The lamp has been drawn for you.
(ii) The cell is a store of chemical energy. Complete the sentences to describe the energy transfers when the circuit is switched on and the lamp is lit.
In the cell, …… energy is transferred to electrical energy in the circuit.
Electrical energy in the circuit is transferred to …… energy and …… energy emitted from the lamp.
(iii) The lamp has a resistance of 8.0 Ω and the potential difference (p.d.) across the lamp is 12 V. Calculate the current in the lamp.
(b) (i) Name the instrument used to measure current in a circuit.
(ii) The wires in the circuit are made of copper. State the name of the particles that flow when there is a current in the wires.
(c) A student connects a 3 Ω and a 4 Ω resistor in series. Calculate the combined resistance of these two resistors in series.
▶️Answer/Explanation
6(a)(i) The circuit diagram should show the cell, switch, and lamp connected in series. The cell should be represented by a long and short line, the switch by a break in the line, and the lamp by a circle with a cross inside.
6(a)(ii) In the cell, chemical energy is transferred to electrical energy in the circuit. Electrical energy in the circuit is transferred to light energy and thermal energy emitted from the lamp.
6(a)(iii) Using Ohm’s Law, \( V = IR \), the current \( I \) can be calculated as: \[ I = \frac{V}{R} = \frac{12}{8} = 1.5 \, \text{A} \] So, the current in the lamp is 1.5 A.
6(b)(i) The instrument used to measure current in a circuit is an ammeter.
6(b)(ii) The particles that flow when there is a current in the wires are electrons.
6(c) When resistors are connected in series, their resistances add up. Therefore, the combined resistance is: \[ R_{\text{total}} = R_1 + R_2 = 3 + 4 = 7 \, \Omega \] So, the combined resistance is 7 Ω.
Question
(a) Fig. 12.1 shows an electric circuit.
(i) With the switch closed, ammeter \( A_1 \) shows a reading of 0.5A. State the reading on ammeter \( A_2 \).
▶️Answer/Explanation
Answer: 0.5 A
Explanation: In a series circuit, the current is the same at every point. Therefore, the reading on ammeter \( A_2 \) will be the same as the reading on ammeter \( A_1 \), which is 0.5 A.
(ii) A boy measures the potential difference across a resistor in the circuit. Name the instrument the boy uses to measure the potential difference.
▶️Answer/Explanation
Answer: Voltmeter
Explanation: A voltmeter is used to measure the potential difference (voltage) across a component in a circuit. It is connected in parallel with the component.
(b) Fig. 12.2 shows a circuit with two resistors in parallel.
Identify, from the list, the most likely value of the combined resistance of the resistors in parallel. Explain your answer.
2 Ω 4 Ω 8 Ω 16 Ω
▶️Answer/Explanation
Answer: 2 \(\Omega\)
Explanation: The combined resistance of two resistors in parallel is always less than the smallest individual resistance. In this case, the smallest resistance is 2 \(\Omega\), so the combined resistance will be less than 2 \(\Omega\). The formula for the combined resistance \( R \) of two resistors \( R_1 \) and \( R_2 \) in parallel is:
\[ \frac{1}{R} = \frac{1}{R_1} + \frac{1}{R_2} \]
If \( R_1 = 2 \Omega \) and \( R_2 = 4 \Omega \), then:
\[ \frac{1}{R} = \frac{1}{2} + \frac{1}{4} = \frac{3}{4} \]
\[ R = \frac{4}{3} \Omega \approx 1.33 \Omega \]
Thus, the combined resistance is less than 2 \(\Omega\), and the most likely value from the list is 2 \(\Omega\).
(c) Complete the sentences using the words in the list. You can use each word once, more than once or not at all.
current potential difference e.m.f. resistance
The flow of charge in a circuit is called the ……
…… is a measure of the difficulty for a charge to flow in an electrical circuit.
▶️Answer/Explanation
Answer: current, resistance
Explanation: The flow of charge in a circuit is called the current. Resistance is a measure of the difficulty for a charge to flow in an electrical circuit.
(d) One of the wires in the circuit was investigated to see the pattern of the magnetic field around it. On Fig. 12.3 draw the expected pattern and direction of the magnetic field on the square piece of card.
▶️Answer/Explanation
Answer: The magnetic field lines should be concentric circles around the wire, with the direction of the field determined by the right-hand rule (thumb points in the direction of current, fingers curl in the direction of the magnetic field).
Explanation: When current flows through a wire, it generates a magnetic field around the wire. The field lines form concentric circles around the wire, and the direction of the field can be determined using the right-hand rule. If the current is flowing upwards, the magnetic field lines will be clockwise when viewed from above.