1. What is the force that keeps things moving in a circle?
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Other questions in this quiz
2. 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
3. Pressure in a liquid is..
- difficult to see
- transmitted equally in all directions
- hard to measure
4. What type of lens is used for short sighted people?
5. What is refractive index?
- The ratio of speed to light in a vacuum to in the medium
- the incident ray parallel to the principal focus
- The refracted ray parallel to the principal focus