CIE iGCSE Co-Ordinated Science P3.1 General properties of waves Exam Style Questions Paper 3
Question
Bats use the reflection of sound waves to determine the position of objects.
Fig. 6.1 shows a bat, and a moth flying in front of the bat.
(a) State the name given to a reflected sound wave. (Topic – P3.4)
▶️Answer/Explanation
Echo
Explanation: An echo is the reflection of sound waves off a surface, which is how bats detect objects in their environment.
(b) Some bats are able to detect ultraviolet radiation. Ultraviolet radiation is part of the electromagnetic spectrum. (Topic – P3.3)
(i) On the incomplete electromagnetic spectrum shown in Fig. 6.2, place ultraviolet in the correct position.
▶️Answer/Explanation
Ultraviolet should be placed between X-rays and infrared.
Explanation: The electromagnetic spectrum is ordered by wavelength and frequency. Ultraviolet (UV) radiation has a shorter wavelength and higher frequency than visible light but longer wavelength and lower frequency than X-rays.
(ii) State which part of the electromagnetic spectrum has the lowest frequency.
▶️Answer/Explanation
Radio waves
Explanation: Radio waves have the longest wavelength and the lowest frequency in the electromagnetic spectrum.
(c) A bat produces a sound wave with a frequency of 200 kHz and a wavelength of 0.0016 m.
(i) Draw straight lines to link each wave term to its definition. (Topic – P3.1)
▶️Answer/Explanation
Amplitude – Maximum displacement of points on a wave
Frequency – Number of waves passing a fixed point per second
Wavelength – Distance between the peaks on consecutive waves
Explanation: Amplitude is the height of the wave, frequency is how often the wave passes a point, and wavelength is the distance between two consecutive peaks or troughs.
(ii) Explain why a human cannot hear the sound emitted by the bat. (Topic – P3.4)
▶️Answer/Explanation
Humans cannot hear sounds with frequencies above 20 kHz.
Explanation: The human hearing range is typically between 20 Hz and 20 kHz. The bat’s sound wave has a frequency of 200 kHz, which is well above the upper limit of human hearing.
(iii) The bat changes the frequency of the sound it produces from 200 kHz to 250 kHz. State what happens to the pitch of the sound. (Topic – P3.4)
▶️Answer/Explanation
The pitch increases.
Explanation: Pitch is directly related to frequency. As the frequency increases from 200 kHz to 250 kHz, the pitch of the sound also increases.