CIE iGCSE Co-Ordinated Science P2.3.3 Radiation Exam Style Questions Paper 4
Question
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P3.1 — General properties of waves (Parts (a) & (b))
• Topic P3.2.3 — Thin converging lens (Part (c)(i) & (c)(ii))
• Topic P2.3.3 — Radiation / P2.3.4 — Consequences of thermal energy transfer (Part (d))
▶️ Answer/Explanation
(a) Amplitude (A) and Wavelength (W) on Fig. 11.1:
• Amplitude (A): Vertical double-headed arrow from the equilibrium position (middle line) to the crest or trough.
• Wavelength (W): Horizontal double-headed arrow between two consecutive crests (or troughs).
(b) Wave speed calculation:
\(v = f\lambda\)
\(v = 0.50 \times 0.078 = 0.039\text{ m/s}\)
(c)(i) Ray diagram for converging lens:
• Draw a ray from the top of the object parallel to the principal axis, which refracts through the focal point (F) on the other side.
• Draw a ray from the top of the object straight through the centre of the lens (undeviated).
• The image is formed where these two refracted rays meet.
• The image is inverted (upside down) and drawn with an arrow below the principal axis.
(c)(ii) Characteristics of the image when object is within focal length:
• Upright (same orientation as the object).
• Magnified (larger than the object).
• Virtual (cannot be projected on a screen; rays appear to diverge from the image).
(d) Daytime and nighttime temperature changes:
Daytime: The temperature of the Earth rises because the energy absorbed from the Sun (incoming infrared radiation) is greater than the energy emitted by the Earth back into space.
Nighttime: The temperature of the Earth falls because there is no incoming solar radiation, so the energy emitted by the Earth is greater than the energy absorbed.
Question
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P6.2.2 — Life cycle of stars (Part (a))
• Topic P6.2.1 — The Sun as a star (Part (b)(i))
• Topic P2.3.2 — Convection (Part (b)(ii))
• Topic P2.3.3 — Radiation (Part (b)(iii))
• Topic P6.2.3 — Galaxies and the Universe (Part (c))
▶️ Answer/Explanation
(a) New stars, planets, or protostars may form from a nebula.
The material from a supernova explosion forms a nebula (cloud of gas and dust), which can collapse under gravity to form new stars and planetary systems.
(b)(i) Energy release in a star:
• Energy is released by nuclear fusion.
• Hydrogen nuclei fuse together to form helium nuclei.
• This process releases vast amounts of energy in the form of electromagnetic radiation (including light and heat).
(b)(ii) Convection in the Sun’s outer layers:
• Hot gas near the core becomes less dense and rises.
• As it rises, it cools and becomes more dense.
• The cooled gas sinks back down, creating convection currents that transfer energy outward.
(b)(iii) Surface design to limit temperature:
• Colour: White or silver (to reflect most incident radiation)
• Texture: Shiny or smooth (to reduce absorption of radiation)
Light colours reflect more radiation (poor absorbers), while shiny surfaces are poor emitters of thermal radiation.
(c) Completed sentences:
The Universe initially expanded from a place of high density (or temperature).
The Universe is still expanding.
The Universe is approximately 13.8 billion years old.