1. What is the focal length?
- the distance from the centre of the lens to the principal focus
- The distance from each of the principal focuses
- The distance from the eye to the lens
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Other questions in this quiz
2. How can you tell something is a real image?
- it can be seen on a TV
- the light can produce an image on the screen
- it can be seen with a magnifying glass
3. What type of lens is used for long sighted people?
4. What is refractive index?
- The refracted ray parallel to the principal focus
- The ratio of speed to light in a vacuum to in the medium
- the incident ray parallel to the principal focus
5. Pressure in a liquid is..
- transmitted equally in all directions
- hard to measure
- difficult to see