Course: Combined and Separate | Find each scene on YouTube, watch it, then answer the questions. Write your answers on paper first, then tap Show answer.
Equations and data: v = fλ · T = 1 ÷ f · s = vt · magnification = image height ÷ object height
Speed of light (all EM waves) = 3 × 10⁸ m/s · Speed of sound in air ≈ 340 m/s · Speed of sound in water ≈ 1500 m/s
1. Finding Nemo – Dory speaks whale
🎬 The scene: Dory tries to talk to a whale with long, low, drawn-out sounds.
Q1 (F) Is sound a transverse or a longitudinal wave? Describe how the particles move.
Show answer
Longitudinal. The particles vibrate parallel to the direction the wave travels, making compressions and rarefactions.
Q2 (F/H) A whale call has a frequency of 20 Hz and travels through water at 1500 m/s. Calculate its wavelength.
Show answer
λ = v ÷ f = 1500 ÷ 20 = 75 m
Q3 (H) Dory makes a long, low sound. What does “low” mean in terms of frequency? Why does sound travel faster in water than in air?
Show answer
A low pitch means a low frequency. Sound travels faster in water because the particles are closer together, so the vibrations pass from particle to particle more quickly.
2. Jurassic Park – the ripples in the water glass
🎬 The scene: The famous glass of water on the car dashboard rippling as the T-rex approaches. The search also finds behind-the-scenes videos showing it was done with a guitar string – a great option if you’d rather avoid the scary part.
Q1 (F) Are the ripples on the water surface transverse or longitudinal?
Show answer
Transverse – the water surface moves up and down, at right angles to the direction the ripples travel.
Q2 (F/H) The ripples have a frequency of 5 Hz and a wavelength of 0.02 m. Calculate their speed.
Show answer
v = fλ = 5 × 0.02 = 0.1 m/s
Q3 (H, Separate) In the film, footsteps send vibrations through the ground. Earthquakes send P-waves and S-waves. Which can travel through liquids, and what does this tell us about the Earth’s core?
Show answer
P-waves (longitudinal) travel through solids and liquids; S-waves (transverse) only through solids. S-waves don’t reach the opposite side of the Earth, showing that the outer core is liquid.
3. Finding Dory – Bailey’s echolocation
🎬 The scene: Bailey the beluga discovers his echolocation works and uses it to guide Dory through the pipes.
Q1 (F) What is ultrasound?
Show answer
Sound with a frequency above 20 000 Hz (20 kHz) – too high for humans to hear.
Q2 (F/H) Bailey’s click returns as an echo after 0.4 s. Sound travels at 1500 m/s in water. How far away is Dory?
Show answer
Total distance = 1500 × 0.4 = 600 m. The sound goes there and back, so Dory is 600 ÷ 2 = 300 m away.
Q3 (H, Separate) Give two human uses of echoes from ultrasound, and explain why an echo is produced.
Show answer
Any two: medical scans (e.g. of unborn babies), sonar to find depth or fish, finding cracks in metal. Ultrasound is partly reflected at a boundary between two different materials; the time for the echo to return gives the distance.
4. Toy Story – the baby monitor mission
🎬 The scene: On Andy’s birthday, the green army men spy on the presents and report back by baby monitor.
Q1 (F) The soldiers report back using a baby monitor. Which part of the electromagnetic spectrum does it use?
Show answer
Radio waves.
Q2 (F/H) The monitor transmits at 49 000 000 Hz (49 MHz). Calculate the wavelength.
Show answer
λ = v ÷ f = 300 000 000 ÷ 49 000 000 = 6.1 m (to 2 s.f.)
Q3 (H) Explain how radio waves carry the message to the receiver.
Show answer
Oscillations in an electrical circuit in the transmitter produce radio waves. When the radio waves are absorbed by the receiver’s aerial, they create an alternating current with the same frequency, which is turned back into sound.
5. Cloudy with a Chance of Meatballs – the microwave machine
🎬 The scene: Flint switches on his FLDSMDFR, which uses microwaves to turn water into food – and it shoots up into the sky.
Q1 (F) Flint’s machine uses microwaves. Give two real uses of microwaves.
Show answer
Cooking food and satellite communications (also mobile phones and Wi-Fi).
Q2 (F/H) A microwave oven uses a frequency of 2.45 × 10⁹ Hz. Calculate the wavelength.
Show answer
λ = 3 × 10⁸ ÷ 2.45 × 10⁹ = 0.12 m (about 12 cm)
Q3 (H) Real or fake? Could microwaves turn water into food? What do microwaves actually do to food?
Show answer
Fake. Microwaves only transfer energy. Water molecules in food absorb them and heat up, cooking the food. They cannot change one substance into another.
6. Big Hero 6 – Baymax scans Hiro
🎬 The scene: Baymax inflates for the first time and scans Hiro to check his health.
Q1 (F) Baymax scans Hiro’s body. Real devices check body temperature by detecting which type of EM wave?
Show answer
Infrared radiation.
Q2 (F/H) All objects give out infrared. How does the amount change if a person has a fever?
Show answer
A hotter body gives out more infrared radiation, so the scanner detects a higher reading.
Q3 (H) Hiro’s temperature stays steady at about 37 °C. Explain this in terms of infrared radiation.
Show answer
His body is absorbing and emitting energy at the same rate overall (including energy released inside his body), so his temperature stays constant.
7. Star Wars – an explosion in space
🎬 The scene: The Death Star fires its superlaser and destroys the planet Alderaan – with a huge bang (A New Hope).
Q1 (F) Real or fake? We hear a huge bang when the planet explodes. Could this be heard in space?
Show answer
Fake. Sound needs a medium (particles) to travel through. Space is a vacuum, so there would be silence.
Q2 (F/H) We can see the flash of light, though. Why can light travel through space when sound can’t?
Show answer
Light is an electromagnetic wave – it doesn’t need particles to travel through, so it can cross a vacuum.
Q3 (H) On Earth, you see an explosion 1 km away. How long after the flash do you hear the bang?
Show answer
t = s ÷ v = 1000 ÷ 340 = 2.9 s. The light arrives almost instantly, so the delay is about 2.9 s – the same reason thunder comes after lightning.
8. Toy Story – Sid’s magnifying glass
🎬 The scene: Sid focuses sunlight through a magnifying glass onto Woody’s forehead until it starts to smoke.
Q1 (F, Separate) What type of lens is a magnifying glass? What does it do to parallel rays of sunlight?
Show answer
A convex (converging) lens. It refracts parallel rays so they meet at the principal focus, concentrating the energy onto a small spot – which is why it gets so hot.
Q2 (F/H, Separate) When you look through a magnifying glass at something close, describe the image.
Show answer
Virtual, upright and magnified. (See our ray diagrams page.)
Q3 (H, Separate) Woody’s badge is 1.5 cm tall. Through the lens its image is 6 cm tall. Calculate the magnification.
Show answer
Magnification = 6 ÷ 1.5 = 4 (no units). Never try Sid’s trick – focused sunlight can start fires and burn skin.
9. The Lion King – “Everything the light touches”
🎬 The scene: At sunrise on Pride Rock, Mufasa shows Simba “everything the light touches”.
Q1 (F) White sunlight is a mixture of colours. List them in order of increasing wavelength.
Show answer
Violet, indigo, blue, green, yellow, orange, red – red has the longest wavelength.
Q2 (F/H) Sunlight travels 150 000 000 000 m to reach the Pride Lands. How long does it take?
Show answer
t = s ÷ v = 1.5 × 10¹¹ ÷ 3 × 10⁸ = 500 s (8 minutes 20 seconds)
Q3 (H, Separate) The grass looks green in sunlight. Explain why. What colour would it look under red light?
Show answer
The grass reflects green wavelengths and absorbs the others. Under red light there is no green light to reflect, so it absorbs the red and looks black (or very dark).
10. Frozen 2 – the waves of the Dark Sea
🎬 The scene: Elsa runs across the Dark Sea as huge waves crash around her.
Q1 (F) Define the amplitude and the wavelength of a wave.
Show answer
Amplitude: the maximum displacement of a point from its rest position. Wavelength: the distance from a point on one wave to the same point on the next wave (e.g. crest to crest).
Q2 (F/H) Sea waves have a wavelength of 4 m and a period of 2 s. Calculate the frequency and the wave speed.
Show answer
f = 1 ÷ T = 1 ÷ 2 = 0.5 Hz. v = fλ = 0.5 × 4 = 2 m/s
Q3 (H) Waves transfer energy but not water. Describe what happens to a floating leaf as a wave passes, and how this is evidence for that.
Show answer
The leaf bobs up and down but doesn’t travel along with the wave. The water just oscillates in place, while the energy moves forward.
Teachers: the buttons open a YouTube search, so you can pick whichever upload is currently available. Please watch the clip through before showing it to a class.
