Optics, Light and Its Optical Properties, Reflection, Speed of Light, Refraction.
Step into the fascinating world of Physics Optics with Nokryan.com! For ECAT entry test preparation, knowledge about the behavior of light is really important. This topic covers the basic concepts of optics, which include reflection, refraction, interference, and diffraction, all of which are the foundations of contemporary physics.
Understanding Light and Its Optical Properties
Light is a type of electromagnetic radiation that shows both particle and wave-like properties. The speed of light in a vacuum is around 3.0 × 10⁸ m/s, and the full pathway of light depends on its interaction with different materials that generate all the optical phenomena. Pieces of light hitting surfaces and being reflected or refracted explain the basics we rely on when designing optical instruments.
Reflection and Refraction in Physics Optics
Reflected occurs when light bounces from a surface and follows the law of reflection which states that the angle of incidence and the angle of reflection are the same. Refraction, however, describes light bending as it passes through different mediums, as described by Snell’s Law:
n1sinθ1 = n2sinθ2
where n represents the refractive index of the medium. Understanding these principles is essential for solving ECAT optics-related MCQs.
Interference and Diffraction of Light
Interference is the phenomenon where two or more light waves superimpose to form a resultant wave. Young’s Double-Slit Experiment demonstrated this effect, showing that light behaves as a wave. The condition for constructive interference is given by:
d sin θ = mλ
where d is the slit separation, λ is the wavelength, and m is the order of interference. Conversely, diffraction happens when light bends around the edges of an obstacle or through a small opening, creating regions of light and dark bands.
Speed of Light and Optical Instruments
Light travels at different speeds depending on what material it is passing through. Refraction is used in lenses, prisms, and other optical devices to focus or disperse light. A convex lens can be defined as diverging light rays. In optics, the formula relating the lens curvature and the focal length for a lens is represented by the lens maker’s equation:
1/f = (n-1)(1/r1 – 1/r2)
where f is the focal length, n is the refractive index, and R₁, R₂ are the radii of curvature.
Practical Applications of Physics Optics
Physics optics plays a vital role in technology, including fiber optics, laser technology, and imaging systems. Understanding these concepts is crucial for answering ECAT MCQs correctly.
Entry Test Physics Optics MCQS Online Preparation Sample Paper 1 Questions with Answer
1. Who gave the idea of light as a wave?
- Bragg
- Newton
- Thomas Young
- Huygen correct
2. Can two headlights of the car produce interference
- Partly produce interference correct
- Yes
- None of these
- No
3. An oil surface floating on a water surface exhibits a beautiful color pattern, which is due to
- Interference of light correct
- Diffraction of light
- Reflection of light
- None of these
4. Huygens wavefront which sends out secondary wavelets with a speed equal to
- Speed of propagation greater than wave
- The speed of propagation is less than the wave
- None of these
- The speed of propagation of the wave correct
5. To observe the phenomenon of interference of light, the light should be
- Phase coherence
- Monochromatic
- Coherent sources
- All of these correct
6. Who devised the experimental arrangement in 1801 for studying interference effects of light
- Huygen
- None of these
- Young correct
- Newton
7. If the path difference must be an integral multiple of wavelength
- D Sin θ = λ /m
- D Sin θ = mλ correct
- D Sin θ = m/λ
- Sin θ = md/λ
8. A-line normal to the wavefront is called
- A ray of light correct
- A beam of light
- None of these
- Both
9. The wave propagates in space by the motion of the
- Wavelength
- Particles
- None of these
- Wavefronts correct
10. Light is a type of energy that produces a sensation of
- Sound
- Feeling correct
- Vision
- None of these
11. The light from the sun reaches to earth with wavefronts
- Spherical
- None of these
- Cylindrical
- Plane correct
12. Every point of a wavefront may be considered as a
- The source of the secondary wavefront correct
- Source of wavefront
- None of these
- Source
13. A spherical wavefront is that which has
- A source
- None of these
- An extended source
- A point source correct
14. The idea of light as a wave produced by
- Thomas Young correct
- Newton
- Huygen
- Michelson
15. A plane wavefront is that which has a source
- Nearest
- Near
- None of these
- Distant correct
16. The distance between two concentric wavefronts is
- None of these
- A half wavelength correct
- A wavelength
- Zero
17. The position of a new wavefront after a certain interval of time can be found by constructing a surface that is
- None of these
- A tangent envelope correct
- A tangent
- Curved surface
18. The points on Hagen’s wavefront which sends out secondary wavelets are also
- Source
- Coherent sources of light correct
- Source of secondary wavelets
- None of these
19. Wavefront if the locus of all points in vibration is in the same
- All of these correct
- Wavelength
- Frequency
- Phase
20. Who confirms the wave theory of light?
- Newton
- Neutron
- Michelson
- Thomas Young correct
Entry Test Physics Optics MCQS Online Preparation Sample Paper 2 Questions with Answer
1. The fringe spacing varies directly with
- Phase coherence
- All of these correct
- Light of wavelength λ
- Distance L
2. When ‘θ’ is small then
- cos θ ≈ sin θ
- sin θ ≈ ten θ correct
- None of these
- ten θ ≈ sin θ
3. How the fringe spacing varies as the separation of the slits increases
- Increases very little
- Decreases correct
- Increases
- None of these
4. If d = 0.25 cm Y = 0.059 cm L = 100 cm m=2 then λ is equal to
- 569 nm
- 596 nm
- 567 nm
- 590 nm correct
5. The fringe spacing in case of blue light
- Increases
- None of these
- Decreases correct
- Remains the same
6. The plano-convex lens used in the Newton’s rings are of focal length
- None of these
- Large correct
- Very large
- Small
7. Fringe spacing ∆Y is the distance between two adjacent bring fringes
- ∆Y = Ld/λ
- ∆Y = dλ/L
- ∆Y = Lλ/d m
- ∆Y = Lλ/d correct
8. Colours seen on oily water surface by the incident white light is due to
- Refraction
- Interference correct
- Reflection
- Diffraction
9. If λ = 589 nm d = 1.0 mm L = 225 cm then fringe spacing ∆Y is given by
- 1.37 mm
- 1.33 mm correct
- 1.80 mm
- 1.76 mm
10. Point out the angle/angle at which the sin θ and tan θ have the same value
- 4⁰ and 6⁰
- 2⁰ and 8⁰
- 2⁰ and 4⁰ correct
- 8⁰ and 10⁰
11. If the bright fringe into be observed then we have a relation
- Y = mLd/ λ
- Y = m λL/d correct
- Y = λL/md
- Y = λd/mL
12. In the phenomenon of interference, the bright and dark fringes are of
- Equal width correct
- None of these
- Different width
- Dark fringes are thicker than bright
13. If the path difference must be half-integral number wavelength
- d sin θ = (m + l)λ
- d sin θ = (m + 1/2) 1/λ
- d sin θ = (m + 1/2)n/λ
- d sin θ = (m + 1/2) λ correct
14. If the two reflected waves reinforce each other then the film as seen from the parallel beam of monochromic light will look
- Bright correct
- Sometimes bright and dark
- None of these
- Dark
15. In the thin film, the path difference between two reflected rays depends upon
- Thickness of the film
- All of these correct
- Angle of incidence
- Nature of the film
16. A thin film is a transparent medium whose thickness with the wavelength of light is
- Not comparable
- Both
- None of these
- Comparable correct
17. The fringe spacing in case of red light
- Remains the same
- Decreases
- Increases correct
- None of these
18. If the dark fringe is to be observed then we have a relation
- Y = (m + 1/2) λd/L
- Y = (m + 1/2) dL/λ
- Y = (m + 1/2) λL/d correct
- Y = (m + 1) λL/d
19. If the thickness of the film and angle of incidence are such that two reflected waves cancel each other the film will look
- Bright
- Dark correct
- None of these
- May be partly bright
20. If ‘d’ ‘m’ and fringe spacing ∆Y are known, the interference effect due to light of λ
- None of these
- Cannot be determined
- This can be determined in some cases
- Can be determined correct
Entry Test Physics Optics MCQS Online Preparation Sample Paper 3 Questions with Answer
1. The distance between the two mirrors can be varied by
- Moving glass plate
- Movable mirror correct
- None of these
- Compensator plate
2. The setting of Newton’s rings is
- None of these
- A plano-convex lens (long focal length) and the plane of the glass plate correct
- A plano-convex lens and the plane glass plate
- A plano-convex lens and a simple glass sheet
3. In Newton’s rings the point of contact of the lens and the glass plate the air film is
- Maximum
- Zero correct
- Minimum
- None of these
4. According to the relation for constructive destructive interference, the point of contact has zero thickness of air so it should have
- Conductive interference correct
- None of these
- No interference
- Destructive interference
5. Measurement of a standard meter in terms of the wavelength of red cadmium light is
- 1,563,163.5
- 1,553,363.5
- 1,553,163.5 correct
- 155,553.5
6. Newton’s rings are formed due to
- Refraction
- Diffraction of light
- Interference of light correct
- None of these
7. The principle of Michelson’s interferometers is
- Reflection
- Interference correct
- Dispersion
- Refraction
8. Diffraction of light occurs, due to the interference between rays coming from the same wavefront of
- The different parts correct
- The same parts
- None of these
- Mixed rays
9. Michelson’s interferometer is an instrument used to measure the distance with
- None of these
- Precision
- Extremely high precision correct
- High Precision
10. When the movable mirror moves, the distance λ/4 the total path difference would be?
- 2/4λ correct
- λ
- 2λ
- None of these
11. Due to the Plano-convex lens and the plane glass plate the thickness of air film changes from the center to outward
- Decreasing gradually
- It is constant at the center
- None of these
- Increasing gradually correct
12. The relation between displacement of the mirror ‘L’ and wavelength λ of the light used
- L = λ/2m
- L = mλ/2 correct
- L = 2mλ
- None of these
13. The central point in Newton’s rings is dark due to
- Destructive interference
- Constructive interference
- B and C correct
- Additional path difference λ/2
14. The function of the compensator plate in the interferometer is to With the help of interferometer, we can find the
- Interfere properly
- None of these
- Reflecting light properly
- To equalize the distance of M₁ and M₂ correct
15. When a movable mirror moves λ/4 distance and the light used is 400 nm, then the distance measured highly precise is
- 10¯⁵ mm
- 100 nm
- 10¯⁴nm correct
- 10¯⁶ mm
16. If the light travels in a straight line, the central region should appear
- No effect
- Dark correct
- None of these
- Bright
17. With the help of an interferometer, we can find the
- None of these
- Phase
- Frequency
- Wavelength correct
18. The phenomenon is found to be prominent when the size of the opening (aperture) is
- None of these
- Equal of light used
- Greater than the wavelength of light
- Smaller than the wavelength of light correct
19. Albert A. Michelson devised an interferometer is
- 1881 correct
- 1820
- 1860
- 1845
20. In Young’s double-slit experiment for the interference of light, the central region of the fringe system is
- Bright correct
- None of these
- Dark
- Bright and dark
Nokryan helps you to prepare accordingly. Physics Optics MCQs o for ECAT entry test covering important topics. Doubled down on your technique to teach problem-solving and build confidence to succeed