CIE iGCSE Co-Ordinated Science P2.3.3 Radiation Exam Style Questions Paper 3
Question
Another student wears a white T-shirt in the Sun and does not become as hot.
Explain why.
Most-appropriate topic codes (Cambridge IGCSE Coordinated Sciences 0654):
• Topic P1.2 — Motion (Part (a)(i))
• Topic P1.6.4 — Power (Part (a)(ii))
• Topic P2.2.2 — Melting, boiling and evaporation (Part (b)(i))
• Topic P2.3.3 — Radiation (Part (b)(ii))
• Topic P6.2.1 — The Sun as a star (Part (b)(iii), (b)(iv))
▶️ Answer/Explanation
(a)(i) evidence of total time = 15 (s); v = s/t (in any form) OR (average speed =) 100/15; 6.7 (m/s)
Total time = 3.7 + 3.1 + 2.6 + 2.6 + 3.0 = 15.0 s. Average speed = 100/15 = 6.7 m/s.
(a)(ii) P = W/t (in any form) OR (work done =) 600 × 3.0; 1800; J
Work done = power × time = 600 × 3.0 = 1800 J. The unit for work is the joule (J).
(b)(i) evaporation
Sweating cools the body because the most energetic water particles evaporate from the skin surface, taking thermal energy with them and lowering the skin temperature.
(b)(ii) white absorbs less (thermal) radiation / white reflects more (thermal) radiation
White surfaces reflect most incident radiation, so less thermal energy is absorbed. Black surfaces absorb more radiation, leading to greater heating.
(b)(iii) helium or hydrogen
The Sun is composed mainly of hydrogen (about 75%) and helium (about 25%), with small amounts of other elements.
(b)(iv) infrared; (visible) light; ultraviolet
The Sun emits energy across the electromagnetic spectrum, but most is in the infrared, visible, and ultraviolet regions.
Question
(ii) The air in the tyres warms up during the ride.
Describe how the motion of the gas molecules in the tyres changes during the ride.
(iii) Select the correct word from the list to complete each sentence.
………………………… have a definite volume but take the shape of the container.
(ii) On Fig. 12.1, label the angle of incidence with the letter i.
(ii) State the method of energy transfer through the frame of the bicycle.
(iii) Describe a simple way of testing whether the frame is made from steel or from aluminium.
Most-appropriate topic codes:
• Topic P1.2 / C1.1 — Motion, average speed; states of matter (Part (a))
• Topic P3.2.1 — Reflection of light (Part (b))
• Topic P2.3.3 / P2.3.2 — Radiation, conduction; magnetism test for steel (Part (c))
▶️ Answer/Explanation
(a)(i) 35.3 s
Average \(= \dfrac{35.3+34.7+37.2+35.0+34.3}{5} = 35.3\) s.
(a)(ii) Molecules move faster
As temperature increases, the gas particles gain kinetic energy and move faster.
(a)(iii) Gases; liquids
Gases have no definite shape or volume, expanding to fill their container.
Liquids have a fixed volume but take the shape of their container.
(b)(i) Arrow pointing away from the cyclist, toward the driver
Light travels from the cyclist, reflects off the mirror, and travels onward to the driver’s eye.
(b)(ii) Angle between the incident ray and the normal, labelled i
The angle of incidence i is measured between the incoming ray and the normal line at the mirror surface.
(c)(i) Radiation
Energy travels from the Sun through the vacuum of space as electromagnetic (thermal) radiation.
(c)(ii) Conduction
Heat is transferred through the solid metal frame by conduction, via vibrating particles passing on energy.
(c)(iii) Test with a magnet; steel is attracted, aluminium is not
A magnet placed near the frame will attract steel (a magnetic material) but not aluminium (non-magnetic).