## Optics Physics Quiz | objective questions | Physics General Knowledge Questions | MCQ

**1 >>Light rays from a point object ?**

- (A) radiate in some lines
- (B) radiate only at the front
- (C) radiate in all directions
- (D) radiate only to the side

**2 >>According to Cartesian sign convention ?**

- (A) all distances are measured from the pole of the mirror or the optical centre of the lens
- (B) all distances are measured from the top of the mirror or the lens
- (C) all distances are measured from the bottom of the mirror or the lens
- (D) all distances are measured from infinity

**3 >>According to Cartesian sign convention the heights measured ?**

- (A) upwards with respect to x-axis and normal to the principal axis (x-axis) of the mirror/lens are taken as positive
- (B) downwards with respect to x-axis and normal to the principal axis (x-axis) of the mirror/lens are taken as positive
- (C) leftwards with respect to x-axis and normal to the principal axis (x-axis) of the mirror/lens are taken as positive
- (D) rightwards with respect to x-axis and normal to the principal axis (x-axis) of the mirror/lens are taken as positive

**4 >>Focal length of a mirror is given by ?**

- (A) f = R/2, R=radius of curvature
- (B) f = R
^{2}, R=radius of curvature - (C) f = R, R=radius of curvature
- (D) f = R/4, R=radius of curvature

**5 >>According to the mirror equation ?**

- (A) 1/f=1/u + 1/v
- (B) 1/f=1/u + 2/v
- (C) 2/f= 1/u + 1/v
- (D) 1/f=2/u + 1/v

**6 >>Magnification for spherical mirrors m is given by ?**

- (A) u/v
- (B) (-v)/u
- (C) u/v
- (D) v/u

**7 >>Refraction is ?**

- (A) Change of direction of propagation of light at the interface of two media as light passes from one medium to another
- (B) The change of direction of propagation of light
- (C) Reversal of direction of propagation of light
- (D) None of the above

**8 >>According to Snell’s law ?**

- (A) The ratio of the cosine of the angle of incidence to the cosine of angle of refraction is constant
- (B) The ratio of the sine of the angle of incidence to the sine of angle of refraction is constant
- (C) The ratio of the angle of incidence to the angle of refraction is constant
- (D) The ratio of the tangent of the angle of incidence to the tangent of angle of refraction is constant

**9 >>For a rectangular slab, refraction takes place at ?**

- (A) Two interfaces
- (B) One interfaces
- (C) Four interfaces
- (D) Three interfaces

**10 >>Total internal reflection can take place only if light is travelling from ?**

- (A) No two media
- (B) any two media
- (C) Rarer to denser medium
- (D) Denser to rarer medium

**11 >>Total internal reflection can take place only if ?**

- (A) incidence angle = 1/n21, n21 = refractive index travelling from 2 to 1
- (B) sin(incidence angle) = 1/ n21, n21 = refractive index travelling from 2 to 1
- (C) cos(incidence angle) = 1/n21, n21 = refractive index travelling from 2 to 1
- (D) tan(incidence angle) = 1/n21, n21 = refractive index travelling from 2 to 1

**12 >>Optical fibre communication uses the principle of ?**

- (A) light scattering
- (B) least action
- (C) Total internal reflection
- (D) light path reversibility

**13 >>For small angles Snell’s law becomes ?**

- (A) n
_{1}i = n_{2} - (B) n
_{1}i = n_{2}r - (C) i = r
- (D) n
_{1}= n_{2}r

**14 >>Thin lens approximation for a lens is ?**

- (A) 1/v+1/u=1/f
- (B) 1/v+1/u= -1/f
- (C) 1/v - 1/u=1/f
- (D) 1/v - 1/u= -1/f

**15 >>Two insulated charged copper spheres A and B have their centres separated by a distance of 50 cm and have identical sizes. A third sphere of the same size but uncharged is brought in contact with the first, then brought in contact with the second, and finally removed from both. What is the new force of repulsion between A and B? ?**

- (A) 5.7×10
^{−3}/N - (B) 6.7×10
^{−3}/N - (C) 4.7×10
^{−3}/N - (D) 3.7×10
^{−3}/N

**16 >>Magnification produced by a lens m is given by ?**

- (A) v/u
- (B) (u)/v
- (C) (-u)/v
- (D) (-v)/u

**17 >>The power P of a lens is given by the approximate formula ?**

- (A) 2/f
- (B) 3/f
- (C) 1/2f
- (D) 1/f

**18 >>Domestic power supply in India is ?**

- (A) 110 V 60 Hz
- (B) 416 V 60 Hz
- (C) 230 V 50 Hz
- (D) 24 V DC

**19 >>If several thin lenses of focal length f1,f2,f3, … are in contact, the effective focal length is ?**

- (A) 1/f=1/f1 − 1/f2 + 1/f3 +…
- (B) 1/f=1/f1 + 1/f2 + 1/f3 +…
- (C) 1/f=1/f1 + 1/f2 - 1/f3 +…
- (D) 1/f=1/f1 + 1/f2 + 1/f3 +…

**20 >>At the minimum deviation D, the refracted ray inside the prism ?**

- (A) becomes parallel to its sides
- (B) becomes perpendicular to its base
- (C) becomes parallel to its base.
- (D) becomes at acute angle to its base

**21 >>Is light a particle or a wave? ?**

- (A) Both particle and wave approaches help us understand different phenomenon
- (B) Light is schizophrenic i.e. sometimes it behaves like a particle and other times like a wave.
- (C) Light is a set of particles
- (D) Light is a set of waves

**22 >>The propagation of light is best described by ?**

- (A) dual / schizophrenic model
- (B) a wave model
- (C) particle model
- (D) None of the above

**23 >>Emission and absorption is best described by ?**

- (A) a wave model
- (B) particle model
- (C) dual / schizophrenic model
- (D) None of the above

**24 >>A wave front is ?**

- (A) locus of all adjacent points at which the phase of vibration of a physical quantity associated with the wave is the same
- (B) series of points on the wave with same frequency
- (C) locus of all adjacent points at which the Electric field is the same
- (D) series of points on the wave with same amplitude

**25 >>A ray is an imaginary ?**

- (A) line along the direction at an angle to the travel of the wave
- (B) line along the direction perpendicular to travel of the wave
- (C) line from source to horizon
- (D) line along the direction of travel of the wave

**26 >>According to Huygens principle ?**

- (A) each point on a wave front is a source of secondary waves
- (B) No point on a wave front is a source of secondary waves
- (C) None of the above
- (D) each point on a wave front is a sink of secondary waves

**27 >>According to Huygens construction relation between old and new wave fronts is ?**

- (A) new wave front is the forward envelope of the secondary waves
- (B) new wave front is perpendicular to old wave front
- (C) new wave front is parallel to old wave front
- (D) new wave front is tangential to old wave front

**28 >>Relation between ray and wave front is ?**

- (A) Rays are tangential to wave front
- (B) Rays are parallel to wave front
- (C) Rays are at acute angle to wave front
- (D) Rays are perpendicular to wave front

**29 >>According to superposition principle in relation to displacements produced by a number of waves ?**

- (A) resultant displacement is the vector sum of the displacements produced
- (B) resultant displacement is the scalar sum of the displacements produced
- (C) resultant displacement is the dot product of the displacements produced
- (D) resultant displacement is the arithmetic sum of the displacements produced

**30 >>Two sources of light are coherent if they have ?**

- (A) same frequency and with a constant phase relationship
- (B) different frequency and with a constant phase relationship
- (C) different frequency and random phases
- (D) same frequency and change phase randomly

**31 >>Interference effects of light from two sources can be observed if ?**

- (A) the sources are coherent
- (B) the sources are independent
- (C) the sources are of different frequency
- (D) the sources are different frequency and random phases

**32 >>If we have two coherent sources S1andS2 vibrating in phase, then for an arbitrary point P constructive interference is observed whenever the path difference is ?**

- (A) An integral multiple of wavelength
- (B) A fraction of a wavelength
- (C) An odd multiple of wavelength
- (D) An even multiple of wavelength

**33 >>To radiate signals with high efficiency, the antennas should have a size ?**

- (A) much smaller than the wavelength λ of the signal
- (B) comparable to the wavelength λ of the signal (at least λ4)
- (C) much greater than the wavelength λ of the signal
- (D) none of these

**34 >>In ground wave propagation the earth ?**

- (A) reflects the waves
- (B) amplifies the radiated signal
- (C) none of these
- (D) attenuates the radiated signal as a result of energy absorption by it

**35 >>Ground wave propagation is used for ?**

- (A) High frequency greater than 10GHz
- (B) VLF few MHz
- (C) Low frequency greater than 500 MHz and less than 1GHz
- (D) High frequency greater than 1GHz

**36 >>Referring to the Young’s double slit experiment, Phase difference corresponding to a Path Difference of λ /3 is ?**

- (A) 180
^{∘} - (B) 120
^{∘} - (C) 90
^{∘} - (D) 60
^{∘}

**37 >>Referring to the Young’s double slit experiment, Path Difference corresponding to a Phase difference of π/3 is ?**

- (A) λ/3
- (B) λ/4
- (C) λ/5
- (D) λ/4

**38 >>Referring to the Young’s double slit experiment, if D and d are distance from slit to screen and screen center to point P fringe width is given by ?**

- (A) 2λD/d
- (B) λD/2d
- (C) 3λD/d
- (D) λD/d

**39 >>In general the term diffraction is used ?**

- (A) if two sources are added vectorially
- (B) if large number of sources is added vectorially
- (C) if single source is multiplied by scalar
- (D) None of the above

**40 >>Diffraction also refers to ?**

- (A) the bending of light around an obstacle
- (B) the bending of light in a medium
- (C) the bonding of light to an obstacle
- (D) None of the above