CIE iGCSE Co-Ordinated Science P3.4 Sound Exam Style Questions Paper 4
Question
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P2.1.2 — Particle model / Gas pressure (Part (a)(i))
• Topic P2.1.2 — Particle model / Temperature and particle motion (Part (a)(ii))
• Topic P2.1.3 — Pressure changes / Gas laws (Part (a)(iii))
• Topic P3.4 — Sound / Speed of sound in different media (Part (b)(i))
• Topic P3.4 — Sound / Ultrasound definition (Part (b)(ii))
• Topic P3.4 — Sound / Ultrasound calculations (Part (b)(iii))
▶️ Answer/Explanation
(a)(i) Gas pressure is caused by the collisions of particles with the walls of the container.
Gas particles move randomly in all directions, constantly colliding with the walls of the syringe. Each collision exerts a small force, and the total force per unit area is the gas pressure.
(a)(ii) The average speed of the particles increases.
Heating the gas transfers thermal energy to the particles, increasing their kinetic energy and causing them to move faster on average.
(a)(iii) The particles move faster, so collisions with the walls occur more frequently and with greater force, increasing the pressure.
At constant volume, the particles have less space to move, so the increased speed leads to a higher rate of collisions and a greater force per collision, resulting in higher pressure.
(b)(i) Solid
Sound travels fastest in solids because particles are closely packed together, allowing vibrations to be transferred quickly from particle to particle.
(b)(ii) 20,000 Hz (20 kHz)
Ultrasound is defined as sound waves with frequencies higher than the upper limit of human hearing, which is 20,000 Hz.
(b)(iii)
Step 1: Total distance travelled = speed × time = 1500 × \( 8.0 \times 10^{-5} \) = 0.12 m
Step 2: Depth = total distance ÷ 2 = 0.12 ÷ 2 = 0.060 m
Question
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P3.4 — Sound (Parts a(i), a(ii) & a(iii))
• Topic P3.3 — Electromagnetic spectrum (Parts b(i) & b(ii))
• Topic P3.1 — General properties of waves (Part c)
▶️ Answer/Explanation
(a)(i) Speed of sound in different states:
Slowest: Gases — particles are far apart with weak intermolecular forces, so vibrations are transmitted slowly.
Fastest: Solids — particles are closely packed with strong intermolecular forces, allowing vibrations to be transmitted rapidly.
(a)(ii) How sound travels through air:
Sound travels through air as a longitudinal wave. The vibrating source causes particles in the air to vibrate back and forth parallel to the direction of energy transfer. This creates a series of compressions (regions of higher pressure where particles are closer together) and rarefactions (regions of lower pressure where particles are spread further apart). These disturbances travel through the air as the energy is passed from one particle to the next.
(a)(iii) Frequency range of human hearing:
20 Hz to 20,000 Hz (20 kHz). Humans can hear sounds within this frequency range. Sounds below 20 Hz are infrasound and above 20 kHz are ultrasound.
(b)(i) Use of ultraviolet radiation:
• Detecting fake bank notes (UV light causes fluorescent markings on genuine notes to glow).
• Sterilising water and surfaces (UV radiation kills bacteria and viruses).
• In tanning lamps.
(b)(ii) Danger of ultraviolet radiation:
• Damage to skin cells — overexposure to UV radiation can cause sunburn, premature ageing of the skin, and skin cancer (melanoma).
• Damage to eyes — UV radiation can cause cataracts and other eye conditions.
• Cell mutations — UV radiation can cause DNA damage and mutations in skin cells.
(c) Calculate the wavelength of the infrared wave:
Using the wave equation: \(v = f\lambda\)
\(\lambda = \frac{v}{f} = \frac{3.0 \times 10^8}{2.2 \times 10^{12}}\)
\(\lambda = 1.36 \times 10^{-4} \, \text{m}\)
Wavelength ≈ \(1.4 \times 10^{-4} \, \text{m}\)