REFRACTION - Multiple Choice Questions Q1. The refractive indexes of medium A, B and C are 1.8 , 1.6 and 1.7 respectively. Which of them has smallest critical angle? (i) A (ii) B (iii) C (iv) Insufficient data Q2. A convex lens has focal length of 15 cm & forming an erect image. Position of object may be at ____. (i) 10 cm (ii) 15 cm (iii) 20 cm (iv) 40 cm Q3. The refractive index of a medium is 1.2 . The speed of light in it is ____ m/s. (i) 3 × 10⁸ (ii) 2 × 10⁸ (iii) 2.5 × 10⁸ (iv) None of these Q4. If the focal length of a lens becomes half, its power becomes ____. (i) half (ii) 4 times (iii) 8 times (iv) None of these Q5. For a convex lens, the distance of image is ____. (i) positive (ii) negative (iii) both (i) & (ii) (iv) Insufficient data Q6. A small bulb is placed at the focal point of a converging lens. When the bulb is switched ON , the lens produces ____. (i) a convergent beam of light (ii) a divergent beam of light (iii) a parallel beam of light (iv) a patch
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