Bending light with glass

Science · Waves, Light & Sound · ages 15-16

Name ______________________ Date ____________

Which quantities change when light crosses into water?
- Speed and wavelength
- Frequency only
- Speed, frequency and wavelength
Why does a straw look bent in water?
- Water colours the straw
- Light changes speed entering water and bends
- The glass magnifies everything
Light enters a slower medium. Which way does it bend?
- It never bends
- Away from the normal
- Toward the normal
How does a camera use its converging lens?
- Object inside focus gives a virtual image on film
- Lenses only magnify
- Object beyond focus gives a real inverted image on the sensor
A stamp sits inside the focal length of a converging lens. What image appears?
- Real inverted reduced
- Virtual upright magnified
- Real inverted magnified
Fibre optics carry signals using total internal reflection.
Circle one: True False
Which image description fits a magnifying glass?
- Virtual, upright, magnified
- Real, inverted, reduced
- Real, upright, magnified
A student draws the refracted ray bending away when entering glass. What is wrong?
- Rays never bend
- Entering a slower medium bends toward the normal
- Glass has no effect

Answer key

For grown-ups. Fold this page away before handing over the rest.

Speed and wavelength · The source fixes the frequency, the medium sets the speed.
Light changes speed entering water and bends · A speed change at the boundary bends the ray.
Toward the normal · Slower means toward the normal.
Object beyond focus gives a real inverted image on the sensor · Cameras catch real images on a screen or sensor.
Virtual upright magnified · Inside the focus, rays spread as if from a bigger object behind.
True · Trapped light pipes around corners instead of escaping.
Virtual, upright, magnified · Use the three word habit: real or virtual, upright or inverted, sized.
Entering a slower medium bends toward the normal · The drawing flips the bending rule.