Summary & 50 MCQs with Answers
Ray Optics deals with the behavior of light in terms of rays. It explains reflection, refraction, lenses, mirrors, optical instruments like microscopes and telescopes, lens formula, mirror formula, magnification, and aberrations.
1. Lens formula is given by:
A) 1/f = 1/v - 1/u ✅
B) v = u + f
C> f = uv
D> None
2. Magnification of a lens is:
A) m = v/u ✅
B) m = u/v
C> m = f/v
D> m = v - u
3. Focal length of concave mirror is:
A) f = R/2 ✅
B) f = 2R
C> f = R
D> f = 1/R
4. Power of a lens is:
A) P = 100/f(cm) ✅
B) P = f/100
C> P = 1/f(m)
D> None
5. Real image is formed by:
A) Concave lens ❌
B) Convex lens ✅
C> Plane mirror
D> Convex mirror
6. Convex lens forms real image when:
A) Object is outside the focal point ✅
B) Object is at focus
C> Object is at infinity
D> Object is inside focal length
7. Concave lens always forms:
A) Virtual, erect, diminished image ✅
B) Real image
C> Inverted image
D> Magnified image
8. Total magnification of a microscope:
A) Product of objective and eyepiece magnifications ✅
B) Sum of magnifications
C> Only objective magnification
D> Only eyepiece magnification
9. Principal focus of concave mirror:
A) Point where parallel rays converge ✅
B) Point where rays diverge
C> Point behind mirror
D> At infinity
10. Telescope resolves distant objects using:
A) Two lenses – objective and eyepiece ✅
B) Single lens
C> Mirror only
D> Prism
11. Lens aberration corrected by:
A) Using combination of lenses ✅
B) Increasing aperture
C> Reducing focal length
D> None
12. Spherical aberration occurs due to:
A) Spherical lens surfaces ✅
B) Chromatic effect
C> Lens thickness
D> Mirror curvature
13. Chromatic aberration is corrected using:
A) Achromatic doublet ✅
B) Single convex lens
C> Plane mirror
D> Convex lens alone
14. Newton’s formula for lens:
A) x·x' = f² ✅
B) 1/f = 1/v - 1/u
C> v = u + f
D> None
15. Refracting telescope forms:
A) Real inverted image ✅
B) Virtual erect image
C> Virtual inverted
D> None
16. Eye lens focuses image on retina by:
A) Changing curvature of lens ✅
B) Changing pupil size
C> Moving lens forward/backward
D> None
17. Power of a convex lens:
A) Positive ✅
B) Negative
C> Zero
D> Depends on object
18. Magnification of concave mirror for object at infinity:
A) Zero ✅
B) One
C> Infinite
D> Half
19. Real image by concave lens:
A) Not possible ✅
B) Possible
C> Depends on distance
D> Depends on focal length
20. Principal focus of convex lens:
A) Point where parallel rays converge ✅
B) Diverge
C> Behind lens
D> At infinity
21. Lens combination focal length formula:
A) 1/F = 1/f₁ + 1/f₂ - d/(f₁f₂) ✅
B) F = f₁ + f₂
C> F = f₁f₂
D> None
22. Angular magnification of telescope:
A) m = f₀/fₑ ✅
B) m = fₑ/f₀
C> m = f₀ + fₑ
D> m = f₀ - fₑ
23. Real and inverted image by concave mirror:
A) Object outside focus ✅
B) At focus
C> Between focus and pole
D> At infinity
24. Refraction occurs due to:
A) Change in speed of light ✅
B) Reflection
C> Diffraction
D> Polarization
25. Focal length of diverging lens:
A) Negative ✅
B) Positive
C> Zero
D> Infinity
26. Image formed by convex lens of object at 2f:
A) Real, inverted, same size ✅
B) Virtual, erect
C> Diminished, real
D> Magnified, virtual
27. Eyepiece of microscope acts as:
A) Magnifier ✅
B) Objective
C> Mirror
D> Lens combination
28. Objective of telescope forms:
A) Real image ✅
B) Virtual image
C> Erect image
D> Inverted image
29. Magnification of simple magnifier:
A) M = 25/f ✅
B) M = f/25
C> M = f
D> None
30. Microscope total magnification:
A) m = m₀ × mₑ ✅
B) m = m₀ + mₑ
C> m = m₀/mₑ
D> m = mₑ/m₀
31. Concave mirror image at infinity:
A) Real, highly diminished ✅
B) Virtual
C> Erect
D> None
32. Real image by convex lens can be:
A) Magnified, diminished, same size ✅
B) Only magnified
C> Only diminished
D> None
33. Telescope eyepiece forms:
A) Virtual image ✅
B) Real image
C> Inverted image
D> None
34. Lensmaker formula:
A) 1/f = (n-1)(1/R₁ - 1/R₂) ✅
B) f = R₁ + R₂
C> f = R₁·R₂
D> None
35. Focal length of combination of lenses in contact:
A) 1/F = 1/f₁ + 1/f₂ ✅
B) F = f₁ + f₂
C> F = f₁·f₂
D> None
36. Prism deviates light due to:
A) Refraction ✅
B) Reflection
C> Diffraction
D> Polarization
37. Dispersion of light occurs because:
A) Refractive index varies with wavelength ✅
B) Reflection
C> Diffraction
D> Polarization
38. Magnifying glass forms:
A) Virtual, erect, magnified image ✅
B) Real image
C> Diminished image
D> Inverted image
39. Focal length of concave lens is:
A) Negative ✅
B) Positive
C> Zero
D> Infinity
40. Real and inverted image by convex lens occurs when object is:
A) Outside focal length ✅
B) At focus
C> Inside focus
D> At infinity
41. Lateral magnification is:
A) Image height / object height ✅
B) Object height / image height
C> 1
D> None
42. Real image distance is positive for:
A) Convex lens, concave mirror ✅
B) Concave lens
C> Convex mirror
D> Plane mirror
43. Virtual image distance is:
A) Negative ✅
B) Positive
C> Zero
D> Infinity
44. Angular magnification of microscope:
A) m = L/fₑ × m₀ ✅
B) m = fₑ/L
C> m = f₀/fₑ
D> None
45. Minimum distance of distinct vision:
A) 25 cm ✅
B) 20 cm
C> 30 cm
D> 50 cm
46. Human eye cannot focus objects closer than:
A) 25 cm ✅
B) 50 cm
C> 10 cm
D> 100 cm
47. Near point of normal eye:
A) 25 cm ✅
B) 50 cm
C> Infinity
D> 10 cm
48. Pinhole camera forms image:
A) Real, inverted ✅
B) Virtual
C> Erect
D> None
49. Camera lens acts as:
A) Convex lens ✅
B) Concave lens
C> Plane lens
D> Diverging lens
50. Image by plane mirror is:
A) Virtual, erect, same size ✅
B) Real, inverted
C> Diminished
D> Magnified