CIE iGCSE Co-Ordinated Science P6.2.3 Galaxies and the Universe Exam Style Questions Paper 3
Question
State what has been added to or removed from the car for it to become charged.
State the type of energy stored in the fuel.
Explain why this is.
Complete the sentences to describe how a solar cell can provide energy.
Light energy from the …………….. is absorbed by the solar cell.
The solar cell changes the light energy to ………………. energy.
The turning effect of the motor can be increased by increasing the number of turns on the coil in the motor.
State one other way to increase the turning effect of the d.c. motor.
The lamps are connected in parallel.
Complete the circuit diagram in Fig. 6.1 to show the two lamps connected in parallel, both controlled by one switch.
The battery has been drawn for you.
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P1.6.1 — Energy (Parts (a)(i), (a)(iii), (a)(iv))
• Topic P4.2.1 — Electrical charge (Part (a)(ii))
• Topic P6.2.3 — Galaxies and the Universe (Part (b))
• Topic P4.5.5 — The d.c. motor (Part (c))
• Topic P4.5.1 — Electromagnetic induction (Part (d)(i))
• Topic P4.5.2 — The a.c. generator (Part (d)(ii))
• Topic P4.5.6 — The transformer (Part (d)(ii))
▶️ Answer/Explanation
(a)(i) Kinetic energy
A moving object possesses kinetic energy because of its motion.
The faster the car moves, the greater its kinetic energy.
Kinetic energy depends on both the mass and speed of the car.
(a)(ii) Electrons
Electrostatic charging occurs when electrons are transferred between surfaces.
Friction between the car and the air (or road) causes electrons to be added to or removed from the car.
This leaves the car with an overall electric charge.
(a)(iii) Chemical potential energy
Fuel stores energy in the chemical bonds of its molecules.
This is released as thermal energy during combustion in the engine.
The energy is described as chemical potential energy.
(a)(iv)
Not all of the chemical energy is converted into useful kinetic energy.
Some energy is transferred to thermal energy due to friction in moving parts.
Some energy is also transferred as sound energy, and both are lost to the surroundings.
(b) Sun; electrical
Light energy from the Sun reaches the solar cell.
The solar cell absorbs this light energy.
It then converts (transfers) the light energy into electrical energy.
(c) Increase the strength of the magnetic field, or increase the current
The turning effect (torque) on the coil depends on the magnetic field strength, current, and number of turns.
Increasing the current passing through the coil increases the force on it.
A stronger magnetic field also increases the turning effect for the same current.
(d)(i)
The circuit is drawn with the two lamps on separate parallel branches.
Both branches connect back to the same battery, so each lamp receives the full battery voltage.
A single switch is placed in the main circuit (before the branches split) so that it controls both lamps together.
(d)(ii) If one lamp fails, the other still lights up
In a parallel circuit, each lamp is connected on its own independent branch.
If one branch breaks (lamp fails), current can still flow through the other branch.
This means the remaining lamp continues to work normally.
Question
A detector records the radioactive emissions from the sample.
The sample is moved away from the detector.
Explain why there is still some radiation detected by the radiation detector.
Suggest a source of this radiation.
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654, 2025–2027 syllabus):
• Topic P3.2.3 — Thin converging lens (Part (a)(i)–(ii))
• Topic P3.3 — Electromagnetic spectrum (Part (a)(iii))
• Topic P5.2.5 — Applications and safety precautions (Part (a)(iv))
• Topic P5.2.2 — The three types of nuclear emission (Part (b))
• Topic P6.2.3 — Galaxies and the Universe (Part (c))
▶️ Answer/Explanation
(a)(i)
The focal length is the distance from the centre of the lens to the point where parallel rays converge.
A double-headed arrow should be drawn along the axis from the lens to the principal focus.
(a)(ii) F
The principal focus is the point where all the parallel light rays meet after passing through the lens.
This point should be labelled F on the axis where the rays converge on the screen.
(a)(iii)
The electromagnetic spectrum in order of increasing wavelength is: gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, radio waves.
Visible light should therefore be written in the empty box immediately after ultraviolet.
(a)(iv)
A safety precaution is that the operator stands behind a lead screen, or leaves the room, while the X-ray is taken.
Lead absorbs X-rays and so reduces the operator’s exposure to ionising radiation.
(b)(i) alpha particles and gamma rays
Alpha (\( \alpha \)), beta (\( \beta \)) and gamma (\( \gamma \)) radiation, emitted from radioactive decay, are all forms of ionising radiation.
Any two of these three (other than X-rays) are acceptable.
(b)(ii)
Ionising radiation can damage cells by breaking chemical bonds in DNA.
This can cause mutations, which may lead to cancer or other genetic disorders.
(c)
Radiation is still detected because of background radiation, which is present everywhere in the environment.
This background radiation comes from natural sources such as cosmic rays from space, and radioactive substances in rocks, soil and plants.