CBSE Class-X
Subject – Science
Topic- Optical Instrument and Human Eye

Q.1) Cinematography is based on which principle? ( 1 mark )

(Q.2) Least distance of vision for a normal eye is ( 1 mark )
(a) 25 cm
(b) 1 m
(c) 30m
(d) Infinity

(Q.3) In an eye, where is image formed? ( 1 mark )

(Q.4) What is iris? ( 1 mark )

(Q.5) Where is far point located for a normal eye? ( 1 mark )

(Q.6) Cylindrical lenses are used to correct which type of defects of vision? ( 1 mark )

(Q.7) Hypermetropia is corrected by which type of lens? ( 1 mark )

(Q.8) What is the cause of cataract? ( 1 mark )

(Q.9) What is least distance of distinct vision? ( 1 mark )

(Q.10) What is a simple microscope? ( 1 mark )

(Q.11) In spectrum which colour bends least? ( 1 mark )

(Q.12) Cataract is a condition ( 1 mark )
(a) When the crystalline lens becomes milky and cloudy.
(b) There is no loss of vision.
(c) It cannot be cured.
(d) Eye can not identify colours

(Q.13) Which of the following does not describe working of the human eye?( 1 mark )
(a) The lens system forms an image on a light sensitive screen called the retina.
(b) Light enters the eye through a thin membrane called the cornea.
(c) Rainbow is formed due to splitting of white light.
(d) Iris is a dark muscular diaphragm that controls the size of the pupil for regulating the amount of light entering into the eye.

(Q.14) Human eye is one of the most valuable and sensitive organ that ( 1 mark )
(a) Enables us to see the wonderful world and colours around us
(b) Can not identify the objects
(c) Is like a telescope
(d) Cannot help us to distinguish things

(Q.15) Iris contracts the pupil ( 1 mark )
(a) In bright light
(b) To allow more light to enter
(c) In darkness
(d) To protect from danger

(Q.16) Electrical signals generated by light sensitive cells of retina are sent to the brain via (1 mark )
(a) Motor nerves
(b) Optic nerves
(c) auditory nerves
(d) Spinal cord

(Q.17) Accommodation of a human eye is the property of ( 1 mark )
(a) The eye lens to adjust its focal length
(b) The eye to see different colors
(c) Filling the eyes with tears
(d) Ability to adjust the size of image

(Q.18) The eye lens forms a ___________ and _________ image of the object on the retina. ( 1 mark )
(a) Virtual and erect
(b) Real and inverted
(c) Real and erect
(d) Virtual and erect

(Q.19) Light sensitive cells get activated on ( 1 mark )
(a) Illumination
(b) Seeing the different colors
(c) Facing opaque objects
(d) Receiving message from the brain

(Q.20) Color blindness is the name given to ( 1 mark )
(a) Inability to distinguish between colors
(b) Inability to see anything
(c) Inability to see in dark
(d) Inability to see in bright light

(Q.21) In eye, light enters through a thin membrane called ( 1 mark )
(a) Cornea
(b) Retina
(c) Pupil
(d) Iris

(Q.22) A person is not able to see distant objects clearly, because ( 1 mark )
(a) He is suffering from myopia
(b) The defect can be rectified by using a convex lens
(c) The defect can be rectified by using a convex mirror
(d) Focal length of the eye lens is too large

(Q.23) Hypermetropia is also known as far sightedness because ( 1 mark )
(a) The person is not able to see clearly the distant objects, but can see near objects clearly
(b) The person is able to see clearly the distant objects, but not near objects
(c) The person is not able to see clearly the distant or near objects
(d) The person is able to see clearly the distant or near objects

(Q.24) Presbyopia can be corrected by ( 1 mark )
(a) Using bifocal lenses
(b) Using concave lenses only.
(c) Using binoculars
(d) Using sunglasses

(Q.25) The shape of the triangular prism ( 1 mark )
(a) Makes the emergent ray bend at angle to the direction of the incident ray
(b) Does not causes dispersion of the light.
(c) Makes emergent ray ant parallel to the incident ray
(d) Direction of emergent ray is free from the shape of prism

(Q.26) Splitting of white light on passage through a triangular prism ( 1 mark )
(a) Takes place due to the base of the prism
(b) Is known as dispersion of light
(c) Is a band of six colors known as spectrum
(d) Is called interference

(Q.27) Dispersion of white light takes place because _________.Choose the most appropriate option. ( 1 mark )
(a) Different colors of light bend through different angles with the incident ray.
(b) The red light bends the least and the violet light bends the most.
(c) Prism is made up of glass.
(d) Refractive index of glass is not uniform in the prism

(Q.28) Placement of another identical prism in an inverted position with respect to the first and allowing the colors of spectrum to pass through it will ( 1 mark )
(a) Change the spectrum into white light
(b) Change the spectrum into a black band
(c) Keep the spectrum as before
(d) Split into more colors

(Q.29) Atmospheric refraction occurs because ( 1 mark )
(a) Light is traveling through vacuum and air
(b) Refractive index of atmosphere keeps changing because its physical conditions do not remain same
(c) Light suffers total internal reflection
(d) Light suffers dispersion

(Q.30) Twinkling of a star is due to ( 1 mark )
(a) Atmospheric refraction of sunlight
(b) Atmospheric refraction of starlight
(c) Lightning in the sky
(d) Due to total internal reflection

(Q.31) The path of light passing through a clear solution is not visible, but becomes visible through a colloid ( 1 mark )
(a) Because light is scattered by relatively larger particles
(b) Because light is getting refracted
(c) Because light is getting refracted as well reflected
(d) Because light is transmitted

(Q.32) Which one of the following is the correct option? ( 1 mark )
(a) Size of scattering particles – Dispersion of light
(b) Very fine scattering particles – Blue light gets scattered
(c) Large scattering particles – No dispersion or scattering of light
(d) Opaque particles – Tyndall effect

(Q.33) The sky appears blue because ( 1 mark )
(a) Molecules of air and other particles in the atmosphere are bigger than wavelength of visible light.
(b) Light of shorter wavelengths at the blue end are scattered more than the red light whose wavelength is 1.8 times.
(c) The scattered blue light do not enters our eyes.
(d) Sky is itself blue in color

(Q.34) ‘Danger’ signal lights are usually red in color because ( 1 mark )
(a) It is a dangerous color
(b) It is most scattered by fog or smoke
(c) It has larger wavelength and can be seen from a distance
(d) Red color is good for eye

(Q.35) Far point of a normal human eye is: ( 1 mark )
(a) 100 m
(b) 500 m
(c) 100 Km
(d) Infinity

(Q.36) During transplantation of eye, ___ is transplanted. ( 1 mark )
(a) Lens
(b) Retina
(c) Cornea
(d) Iris

(Q.37) The diameter of eyeball is approximately: ( 1 mark )
(a) 2.0 cm
(b) 2.3 cm
(c) 2.5 cm
(d) 2.7 cm

(Q.38) I in VIBGYOR signifies: ( 1 mark )
(a) Indigo
(b) Incident ray
(c) Image
(d) Inverted

(Q.39) What happens to the image distance in the eye when we increase the distance of an object from the eye? ( 2 Marks )

(Q.40) Why does the sky appear dark instead of blue to an astronaut? ( 2 Marks )

(Q.41) Define dispersion and spectrum? ( 2 Marks )

(Q.42) What do you understand by power of accommodation of the eye? ( 2 Marks )

(Q.43) Define least distance of distinct vision. ( 2 Marks )

(Q.44) Why does it take some time to see objects in a dim room when you enter the room from bright sunlight outside? (3Marks )

(Q.45) What is presbyopia? How is it corrected? ( 3 Marks )

Q.46) Why do stars twinkle? ( 3 Marks ) (Q.47) How will you say that white light of the sun is made of seven colors? ( 3 Marks )

(Q.48) The far point of a myopic person is 80cm in front of the eye. What is the nature and power of the lens required to correct the problem? ( 3 Marks )

(Q.49) What is short sightedness or myopia? What causes myopia? How is myopia corrected? ( 5 Marks )