Every card in Waves, light and sound, Year 8: more practice
The whole deck, in order — so you can read it through before your child ever sees it.
- After the eardrum vibrates, what passes the vibration on towards the inner ear?
Three tiny bones in the middle ear
HintSmall linked parts sit between the eardrum and the inner ear.
WhySound waves shake the eardrum, the tiny bones pass the vibration on, and the inner ear turns it into signals that travel to the brain along a nerve.
- A dog whistle makes a sound of 30,000 Hz. Why can most people not hear it?
Its frequency is above 20,000 Hz, the top of the human hearing range
HintCompare 30,000 with the upper limit of what our ears detect.
WhyHumans hear roughly 20 Hz to 20,000 Hz, and the top of the range falls with age. Dogs can hear well above 20,000 Hz.
- Why can you not see a friend standing just round a corner?
Light travels in straight lines, so it cannot bend round the corner to your eyes
HintThink about the route the rays take between a friend and you.
WhyLight only reaches your eyes if there is a clear straight-line path from the object to you.
- A small lamp shines on an object and makes a shadow on a wall. What happens to the shadow if the lamp moves closer to the object?
The shadow gets bigger
HintRays spread out from the lamp in straight lines. Which rays does the object block?
WhyClose to the object, the lamp sends a wider fan of rays at it, so the object blocks rays reaching a larger area of the wall.
- A ray hits a plane mirror at 20° to the mirror surface. What is the angle of reflection, measured from the normal, in degrees? (number only)
70
HintThe normal is at 90° to the surface.
WhyThe angle of incidence is measured from the normal: 90° − 20° = 70°. The angle of reflection equals it, so it is 70°.
- A ray hits a plane mirror at 40° to the normal. What angle does the reflected ray make with the mirror surface, in degrees? (number only)
50
HintThe normal is at 90° to the surface. Find the reflected ray's angle to the normal first.
WhyThe angle of reflection is 40°, and the normal is at 90° to the surface, so the reflected ray is 90 − 40 = 50° from the mirror.
- An object is 3 m in front of a plane mirror. How far apart are the object and its image, in metres? (number only)
6
HintThe image is as far behind the mirror as the object is in front.
WhyThe image is 3 m behind the mirror, so the distance between object and image is 3 + 3 = 6 m.
- A ray of light travels from air into a glass block at an angle. Which way does it bend?
Towards the normal
HintGlass slows light down.
WhyLight slows down in glass, so its path bends towards the normal. Leaving the block into air it speeds up and bends away from the normal.
- Why does a swimming pool look shallower than it really is when you look into it from above?
Light from the bottom bends as it leaves the water, so it seems to come from a higher point
HintYour brain assumes rays always reach your eyes in a straight line.
WhyThe rays bend away from the normal as they leave the water into air. Traced straight back, they seem to start higher than the real bottom.
- To focus on a close object, does the lens in the eye become thinner or fatter?
Fatter (more curved), so it bends light more
HintClose objects send rays in at a steep angle that needs bending harder.
WhyMuscles squeeze the lens fatter to focus on near objects and let it relax thinner for distant ones, keeping the image sharp on the retina.
1★ KS3-PHYS-WAV-0046
2★ KS3-PHYS-WAV-0047
3★ KS3-PHYS-WAV-0048
4★ KS3-PHYS-WAV-0049
5★ KS3-PHYS-WAV-0050
6★ KS3-PHYS-WAV-0051
7★ KS3-PHYS-WAV-0052
8★ KS3-PHYS-WAV-0053
9★ KS3-PHYS-WAV-0054
10★ KS3-PHYS-WAV-0055
Keep what you learn
Here, nothing is saved. In your child’s own sky every card is scheduled — it comes back just before they’d forget it — and the professor who wrote it is one tap away.