Thin Lenses Quiz
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5 questions, one answer each
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1. What is the effect of a converging lens on a parallel beam of light?
- A. It spreads the rays apart
- B. It brings the rays together at a point
- C. It reflects the rays back
- D. It has no effect on the rays
2. Which type of lens can NEVER form a real image?
- A. Converging lens
- B. Diverging lens
- C. Both types can always form real images
- D. Neither type can form a real image
3. An object is placed closer to a converging lens than its focal length. What kind of image is formed?
- A. Real, inverted, diminished
- B. Virtual, upright, enlarged
- C. Real, upright, same size
- D. Virtual, inverted, diminished
4. A student is short-sighted, meaning distant objects appear blurred because light focuses in front of the retina. Which lens should be used to correct this, and why?
- A. A converging lens, to add extra convergence power
- B. A diverging lens, to spread the rays out before they enter the eye so the focus point moves back onto the retina
- C. A converging lens, to focus the rays even more strongly in front of the retina
- D. Neither type of lens can correct this defect
5. Two lenses are compared: Lens A is convex and thick in the middle; Lens B is concave and thin in the middle. A patient with long-sightedness needs light from near objects, which currently focuses behind their retina, brought forward onto it. Which lens should be prescribed, and what image property will this same lens type always give when used as a magnifying glass?
- A. Lens B; it always gives a real, inverted image when used as a magnifier
- B. Lens A; it always gives a virtual, upright, enlarged image when the object is closer than its focal length
- C. Lens A; it always gives a real, diminished image when used as a magnifier
- D. Lens B; it can give either a real or virtual image depending on distance