Optical Instrument MCQs
Q: Magnifying power of a simple microscope
- Increases with increase in focal length
- Increases with the decrease in focal length
- No effect with decrease or increase with the focal length
- Least distance of distinct vision
Answer: (2) Increases with the decrease in focal length
Q: Magnification of astronomical telescope is
- f0 + fe
- f0/fe
- fe/f0
- (1+f0/fe)L/f0
Answer: (2) f0/fe
Q: The magnifying power of an astronomical telescope is 10 and the focal length of its eye-piece is 20 cm. The focal length of its objective will be
- 200 cm
- 2 cm
- 0.5 cm
- 0.5 x 10–2 cm
Answer: (1) 200 cm
Q: The magnifying power of a telescope is 9. When it is adjusted for parallel rays, the distance between the objective and the eye-piece is found to be 20 cm. The focal lengths of the lenses are
- 18 cm, 2 cm
- 11 cm, 9 cm
- 10 cm, 10 cm
- 15 cm, 5 cm
Answer: (1) 18 cm, 2 cm
Q: In a compound microscope, magnifying power is 95 and the distance of the object from the objective lens is 1/38 cm. The focal length of the objective lens ¼ cm. What is the magnification of eyepiece?
- 5
- 10
- 100
- 200
Answer: (1) 5
Q: A hypermetropic person having “near point” at a distance of 0.75 m puts on spectacles of power 2.5 D. The “near point” now is at
- 0.75 m
- 0.83 m
- 0.26 cm
- 0.26 m
Answer: (4) 0.26 m
Q1: A lens which converges a beam of parallel rays to a point is called
- Diverging (or concave) lens
- Converging (or convex) lens
- Plano concave lens
- Plano-convex lens
Answer: (2) Converging (or convex) lens
Q: The diameter of a lens is called
- Focal length
- Principle axis
- Aperture
- Radius of curvature
Answer: (3) Aperture
Q: In going from a denser to rarer medium a ray of light is
- Undeviated
- Bent away from the normal
- Bent towards the normal
- polarised
Answer: (2) Bent away from the normal
Q: The power of a concave lens is
- Real
- Virtual
- Positive
- negative
Answer: (4) negative
