Light and Optical Systems: Further Practice

Total internal reflection, mirror images, long-sightedness, and why materials look the way they do.

8 questions, free, marked as you go with a worked explanation on every one.

What this covers

Light enters a glass fibre and keeps reflecting off its inner walls instead of escaping, carrying a signal along its length. What is this called?
A flat mirror forms an image of an object standing in front of it. Which best describes that image?
A periscope uses two flat mirrors angled at 45 degrees to let someone see over an obstacle. Which property of light makes this work?
A person who can see distant objects clearly but struggles to focus on close objects has long-sightedness. Where does their eye focus light from a close object, and which lens corrects it?
A pinhole camera has its pinhole 20 cm from the film and 100 cm from an object that is 150 cm tall. How tall is the image formed on the film, in centimetres?
Use the table below, listing whether four different materials let light fully through, scatter it, or block it entirely. Which material is opaque?
Which best explains why the sky appears blue during the day?
Light travels at about 300,000 km per second. The Sun is about 150,000,000 km from Earth. About how many seconds does sunlight take to reach Earth, rounded to the nearest whole number?