LightCopy
1. A light ray passes from air (n = 1.00) into glass (n = 1.50) at an angle of 40°. Which of the following is closest to the angle of refraction?
A) 25.0°
B) 40.0°
C) 45.5°
D) 60.0°
2. A pin appears to be 2 cm above its actual depth when viewed in water. The real depth is 5 cm. What is the refractive index of water?
A) 1.20
B) 1.33
C) 2.50
D) 3.00
3. Which statement best explains why light bends when entering a new medium?
A) Its frequency changes
B) Its speed changes
C) Its amplitude changes
D) The wavefront is absorbed
4. Total internal reflection occurs only when light travels:
A) From air into glass
B) From vacuum into water
C) From a denser to a rarer medium
D) At exactly 90° to the surface
5. Which of the following increases when a ray of light enters a denser medium?
A) Speed
B) Frequency
C) Wavelength
D) Refractive index
6. A prism disperses white light because:
A) Different wavelengths have same speed in glass
B) Different colours have different frequencies
C) Red light refracts more than violet
D) Refractive index varies with wavelength
7. Which optical property is used in fiber optic communication?
A) Diffraction
B) Refraction
C) Total internal reflection
D) Polarisation
8. A converging lens forms a real image that is inverted and diminished. The object must be:
A) Beyond 2F
B) At 2F
C) Between F and 2F
D) At F
9. Which is true for virtual images?
A) They are always inverted
B) They can be projected on a screen
C) They are always formed by diverging lenses
D) They cannot be formed by plane mirrors
10. A ray of light passes undeviated through a glass block. What must be true?
A) It enters at an angle greater than critical angle
B) It enters normally
C) It reflects inside the block
D) The block has no refractive index
11. The critical angle for diamond is 24.4°. What happens when light hits the surface at 25°?
A) It refracts
B) It reflects partially
C) Total internal reflection
D) Dispersion
12. A light ray strikes a mirror at 35°. What is the angle between the incident and reflected rays?
A) 35°
B) 55°
C) 70°
D) 90°
13. What happens to the frequency of light as it enters a denser medium?
A) Increases
B) Decreases
C) Remains constant
D) Becomes zero
14. In which case does the light ray bend away from the normal?
A) Glass to air
B) Air to glass
C) Water to glass
D) Diamond to water
15. What is the magnification of an image formed by a convex lens when the image is same size and real?
A) < 1
B) > 1
C) 1
D) 0
16. Which one of these devices uses total internal reflection?
A) Convex mirror
B) Microscope
C) Endoscope
D) Binoculars
17. Light from a laser is different from light from a bulb because:
A) Laser is non-directional
B) Laser light is monochromatic
C) Bulb light is coherent
D) Laser has multiple wavelengths
18. Which diagram correctly shows light passing from air to water and bending toward the normal?
A) Ray bends away
B) Ray goes undeviated
C) Ray bends toward normal
D) Ray reflects back
19. What is the nature of image formed by a plane mirror?
A) Real, inverted, same size
B) Virtual, upright, enlarged
C) Virtual, upright, same size
D) Real, upright, diminished
20. The principle of reversibility of light implies that:
A) Light travels in curves
B) A ray retraces its path if reversed
C) Reflection does not occur
D) Refraction happens only one way
21. If refractive index = 1.5 and angle of incidence = 60°, what is the angle of refraction?
A) 30°
B) 40°
C) 60°
D) 90°
22. Which of the following best defines refractive index?
A) sin i / sin r
B) speed in medium / speed in air
C) wavelength in vacuum / wavelength in air
D) frequency in vacuum / frequency in glass
23. Which light colour bends most in a prism?
A) Red
B) Green
C) Violet
D) Yellow
24. A diverging lens always forms an image that is:
A) Real, inverted
B) Real, upright
C) Virtual, upright
D) Virtual, inverted
25. When viewing an object through a glass slab, it appears raised due to:
A) Diffraction
B) Total internal reflection
C) Real depth being less than apparent
D) Refraction
26. Which is true for all convex mirrors?
A) Always produce real images
B) Can produce magnified images
C) Always produce virtual, diminished images
D) Never reflect light
27. A beam of parallel rays converge to a point after passing through a lens. The lens is:
A) Concave
B) Diverging
C) Convex
D) Plane
28. Which quantity does NOT change when light enters a new medium?
A) Speed
B) Direction
C) Frequency
D) Wavelength
29. What happens to wavelength of light as it enters a denser medium?
A) Increases
B) Decreases
C) Remains same
D) Becomes infinite
30. Dispersion occurs due to:
A) Interference
B) Different critical angles
C) Different refractive indices for colours
D) Equal velocities of colours
31. Which one is NOT true about virtual images?
A) Cannot be projected
B) Can be seen with eyes
C) Formed on same side as object in lens
D) Always upright and enlarged
32. A convex lens has a focal length of 10 cm. Where should an object be placed to get same size real image?
A) 10 cm
B) 20 cm
C) Between 10–20 cm
D) Beyond 20 cm
33. The critical angle can be calculated using:
A) sin⁻¹(n₂/n₁)
B) sin⁻¹(n₁/n₂)
C) sin(n₁/n₂)
D) n₁/n₂
34. When a ray enters water from air at an angle of 0°, the refraction is:
A) Maximum
B) Minimum
C) Zero
D) Unpredictable
35. What is the purpose of cladding in optical fibers?
A) To reflect light back into core
B) To refract light into air
C) To absorb signal
D) To carry electricity
1. ✅ A) 25.0°
Using Snell’s law: n1sini=n2sinrn_1 sin i = n_2 sin r →
sinr=1⋅sin40°1.5sin r = frac{1 cdot sin 40°}{1.5} ≈ 0.428 → r ≈ 25°.
Wrong options:
B) Incorrect – No bending.
C) Incorrect – Overestimated.
D) Physically implausible – angle too large.
2. ✅ B) 1.33
Refractive index = real depth / apparent depth = 5 / 3.75 ≈ 1.33
Wrong options:
A) Miscalculated
C/D) Unrealistic for water
3. ✅ B) Its speed changes
Speed reduction causes direction change.
Wrong options:
A) Frequency remains unchanged
C) Amplitude doesn’t affect direction
D) Absorption is not the cause of bending
4. ✅ C) From a denser to a rarer medium
TIR only occurs when light tries to pass to a medium of lower refractive index.
Wrong options:
A/B) Wrong direction
D) 90° incidence gives no refraction
5. ✅ D) Refractive index
The refractive index is a material property.
Wrong options:
A) Speed decreases
B) Frequency stays same
C) Wavelength decreases
6. ✅ D) Refractive index varies with wavelength
Shorter wavelengths (e.g., violet) bend more.
Wrong options:
A) Wrong – they do not have same speed
B) Not main cause
C) Reversed – violet bends more
7. ✅ C) Total internal reflection
Light bounces within the fiber core.
Wrong options:
A) Irrelevant here
B) Not enough to trap light
D) Applies to transverse light filtering
8. ✅ A) Beyond 2F
Image is real, inverted, diminished only when object is beyond 2F.
Wrong options:
B) Image would be same size
C) Image would be enlarged
D) At F – no image
9. ✅ C) They are always formed by diverging lenses
Diverging lenses only form virtual images.
Wrong options:
A) Virtual images are upright
B) Cannot be projected
D) Plane mirrors do form virtual images
10. ✅ B) It enters normally
If incidence is 0°, no deviation occurs.
Wrong options:
A) Above critical angle causes TIR
C) No internal reflection here
D) All transparent materials have refractive index
11. ✅ C) Total internal reflection
Incident > critical angle = total reflection.
Wrong options:
A/B) Incorrect application
D) Dispersion is unrelated
12. ✅ C) 70°
Angle between = 2 × angle of incidence = 2 × 35 = 70°
Wrong options:
A/B) Partial misunderstanding
D) 90° occurs at 45° incidence
13. ✅ C) Remains constant
Frequency of light is constant across media.
Wrong options:
A/B) Speed & wavelength change
D) Physically incorrect
14. ✅ A) Glass to air
From denser to rarer → bends away from normal.
Wrong options:
B/C/D) All involve bending toward normal
15. ✅ C) 1
Image same size → magnification = 1
Wrong options:
A/B) Implies different size
D) Not possible unless no image
16. ✅ C) Endoscope
Uses TIR to send light inside body
Wrong options:
A) Curved reflection
B) Uses lenses
D) Uses prisms not fibers
17. ✅ B) Laser light is monochromatic
Single wavelength and coherent
Wrong options:
A) Laser is directional
C) Bulb is incoherent
D) Laser is single wavelength
18. ✅ C) Ray bends toward normal
From air to water – ray slows down, bends toward normal
Wrong options:
A) Reversed
B) Only if normal incidence
D) Not expected unless total internal reflection
19. ✅ C) Virtual, upright, same size
Plane mirrors always do this.
Wrong options:
A) Plane mirrors don’t form real images
B) Not enlarged
D) Real image not formed
20. ✅ B) A ray retraces its path if reversed
Light path is reversible
Wrong options:
A) Light travels straight
C) Reflection always occurs
D) Refraction is two-way
21. ✅ A) 30°
Use Snell’s Law: sin r = sin 60° / 1.5 ≈ 0.577 → r ≈ 30°
Wrong options:
B/C/D) Math doesn’t check
22. ✅ A) sin i / sin r
Snell’s Law: n = sin i / sin r
Wrong options:
B) Reverse
C) Not correct form
D) Frequency doesn’t determine refractive index
23. ✅ C) Violet
Shortest wavelength = most bending
Wrong options:
A) Bends least
B) Midpoint
D) Less than violet
24. ✅ C) Virtual, upright
Always and only produces these
Wrong options:
A/B/D) Diverging lenses never form real images
25. ✅ D) Refraction
Apparent depth is due to bending of light
Wrong options:
A) Not bending mechanism
B) Not applicable
C) Reversed – apparent depth is less
26. ✅ C) Always produce virtual, diminished images
Convex mirrors always do this
Wrong options:
A/B) Can’t produce real or magnified images
D) False
27. ✅ C) Convex
Converging = convex
Wrong options:
A/B) Diverging
D) Doesn’t converge
28. ✅ C) Frequency
Frequency is unchanged
Wrong options:
A/B/D) All affected during medium transition
29. ✅ B) Decreases
Wavelength ∝ speed; speed drops → wavelength drops
Wrong options:
A) Opposite
C) False
D) Not possible
30. ✅ C) Different refractive indices for colours
Each colour bends differently
Wrong options:
A) Not involved
B) Critical angle is not main factor
D) Velocities aren’t equal
31. ✅ D) Always upright and enlarged
They’re upright, but not always enlarged
Wrong options:
A/B/C) All true
32. ✅ B) 20 cm
To get same size real image → object at 2F
Wrong options:
A) Virtual image
C/D) Will alter size
33. ✅ A) sin⁻¹(n₂/n₁)
Critical angle formula
Wrong options:
B–D) Misapplied ratios
34. ✅ C) Zero
Normal incidence = no refraction
Wrong options:
A/B/D) No bending at 0°
35. ✅ A) To reflect light back into core
Cladding ensures TIR
Wrong options:
B) Would cause loss
C) Undesirable
D) Not electrical