1011 + Interview Questions in RAY-OPTICS IN GENERAL AWARENESS Page 8 InterviewSolution

351.	A convex mirror is used to form the image of an object. Which of the following statements is wrong ?A. The image lies between the pole and the focusB. The image is diminished in sizeC. The image is erectD. The image is real
Answer» Correct Answer - d

Discussion

352.	A horizontal ray of light passes through a prism whose apex angle is `4^@` and then strikes a vertical mirror M as shown in Figure. For the ray to become horizontal after reflection, Find the angle by which the mirror must be rotated. A. `2^(@)`B. `3^(@)`C. `4^(@)`D. `1^(@)`
Answer» Correct Answer - A::D

Discussion

353.	A point object is placed at a distance of 10 cm and its real image is formed at a distance of 20 cm from a concave mirror. If the object is moved by 0.1 cm towards the mirror, the image will shift by aboutA. 0.4 cm away from the mirrorB. 0.8 cm away from the mirrorC. 0.4 cm towards the mirrorD. 0.8 cm towards the mirror
Answer» Correct Answer - A From the relation, `(1)/(v)+(1)/(u)=(1)/(f)` We have, `(-dv)/(v^(2))-(du)/(u^(2))=0` `therefore " " dv=(v^(2))/(u^(2))(-du)=((20)/(10))^(2) (0.1)=0.4 cm " "` (away from the mirror)

Discussion

354.	A point object is placed at a distance of 10 cm and its real image is formed at a distance of 20 cm from a concave mirror. If the object is moved by 0.1 cm towards the mirror, the image will shift by aboutA. 0.4 cm away from the mirrorB. 0.4 cm towards the mirrorC. 0.8 cm away from the mirrorD. 0.8 cm towards the mirror
Answer» Correct Answer - a

Discussion

355.	An object is placed 40 cm from a concave mirror of focal length 20 cm. The image formed isA. real,inverted and same in sizeB. real,inverted and smaller in sizeC. virtual,erect and larger in sizeD. virtual,erect and smaller in size
Answer» Correct Answer - A (a) Image formeed is real, inverted and same in size because object is at the centre of curvature of the mirror.

Discussion

356.	An object 0.04 m high is placed at a distance of 0.8 m from a concave mirror of radius of curvature 0.4 m. find the position, nature and the size of the image formed.
Answer» Correct Answer - Real, inverted image of height 1.33 cm at 26.67 cm from the mirror

Discussion

357.	An object 5 cm tall is placed 1 m from a concave spherical mirror which has a radius of curvature of 20 cm. The size of the image isA. 0.11 cmB. 0.5 cmC. 0.55 cmD. 0.60 cm
Answer» Correct Answer - C (c ) We have, `I/O=f/((f-u))` `rArr I/5=(-10)/(-10-(-100))` Size of the image , I=0.55 cm

Discussion

358.	A virtual image three times the size of the object is obtained with a concave mirror of radius of curvature 36cm. The distance of the object from the mirror isA. 5 cmB. 12 cmC. 10 cmD. 20 cm
Answer» Correct Answer - b

Discussion

359.	For a real object, which of the following can produced a real imageA. Plane mirrorB. Concave lensC. Convex mirrorD. Concave mirror
Answer» Correct Answer - d

Discussion

360.	Assertion : If a plane glass slab is placed on the letters of different colours all the letters appear to be raised up to the same height. Reason : Different colours have different wavelengths.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If assertion is f alse but reason is true
Answer» Correct Answer - d

Discussion

361.	Assertion : The polar caps of earth are cold in comparison to equatorial plane. Reason : The radiation absorbed by polar caps is less than the radiation absorbed by equatorial plane.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false
Answer» Correct Answer - c

Discussion

362.	Assertion : The fluorescent tube is considered better than an electric bulb. Reason : Efficiency of fluorescent tube is more than the efficiency of electric bulb.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false
Answer» Correct Answer - a

Discussion

363.	A plane mirror reflects a pencil of light to form a real image. Then the pencil of light incident on the mirror isA. ParallelB. ConvergentC. DivergentD. None of the above
Answer» Correct Answer - b

Discussion

364.	Two vertical plane mirrors are inclined at an angle of `60^(@)` with each other. A ray of light travelling horizontally is reflected first from one mirror and then from the other. The resultant deviation isA. `60^(@)`B. `120^(@)`C. `180^(@)`D. `240^(@)`
Answer» Correct Answer - d

Discussion

365.	A convax lens of focal length `10.0cm`is placed in contact with a convex lens of `15.0cm` focal length ,What is the focal length of the combination.
Answer» for combination of lenses `(1)/(f)=(1)/(f_(1))+(1)/(f_(2))` `=(1)/(10)+(1)/(15)` `=(25)/(150)=(1)/(6)` Therefore,`f=6cm`

Discussion

366.	An object is placed at a distant of `1.50` from a screen and a convex lens placed in between produces an image magnified `4`times on the screen .What is the focal length and the position of the lens.
Answer» The information given in the question ray diagram.It is given that `m=(1)/(O)=-4` Lets lens is placed at a distance of`x` from the object.Then u=-x,and v=(1.5-x) using`m=(v)/(u),"we get"-4=(1.5-x)/(-x)` or 4x=1.5-x or 5x=1.5 Thus x=0.3 metre The lens is placed at a distance of 0.3m from the object (or`1.20m`from the screen) For focal length,we may use `m=(f)/(f+u)` or`-4=(f)/(f+(-0.3))` or`-4f+1.2=f` or`5f=1.2` thus`f=(1.5)/(5)=0.24` The focal length is `0.24m(or 24cm)`

Discussion

367.	If two lenses of `+5` dioptres are mounted at some distance apart, the equivalent power will always be negative if the distance isA. Greater than 40 cmB. Equal to 40 cmC. Equal to 10 cmD. Less than 10 cm
Answer» Correct Answer - a

Discussion

368.	When a glass slab is placed on a cross made on a sheet, the cross appears to be raised by `1cm`. The thickness of the glass is `3cm`. The critical angle for glass isA. `sin^(-1)(0.33)`B. `sin^(-1)(0.5)`C. `sin^(-1)(0.67)`D. `sin^(-1)((sqrt(3))/2)`
Answer» (c) We can write shift `1=3(1-1/(mu))` `implies 1-1/(mu)=1/3` or `1/(mu)=1-1/3=2/3impliesmu=3/2` Now, `1/(sin i_(c))=3/2impliessin i_(c)=2/3` or` i_(c)=sin^(-1)(2/3)impliesi_(c)=sin^(-1)(0.67)`

Discussion

369.	A convex lens produces a real image `m` times the size of the object. What will be the distance of the object from the lens ?A. `((m+1)/(m)) f`B. `( m – 1 ) f `C. `((m-1)/(m))f`D. `(m+1)/(f)`
Answer» Correct Answer - a

Discussion

370.	An object is placed `12 cm` to the left of a converging lens of focal length `8cm`. Another converging lens of `6 cm` focal lengh is placed at a distance of `30 cm` to the right of the first lens. The second lens will produceA. No imageB. A virtual enlarged imageC. A real enlarged imageD. A real smaller image
Answer» Correct Answer - c

Discussion

371.	A convex lens is made up of three different materials as shown in the figure. For a point object placed on its axis, the number of images formed are A. 1B. 5C. 4D. 3
Answer» Correct Answer - d

Discussion

372.	A layered lens is made of materials indicated by shades in the figure. The number of images formed is A. 1B. 2C. 3D. 4
Answer» Correct Answer - (d)

Discussion

373.	Total flux produced by a source of `1 cd ` isA. `(1)/(4pi)`B. `8 pi`C. `4pi`D. `(1)/(8pi)`
Answer» Correct Answer - c

Discussion

374.	A simple telescope used to view distant objects has eyepiece and objective lens of focal lengths of `f_(e)`and`f_(o)`,respectively .then `{:(Coloumn 1,Coloumn 2),((A) "Intensity of light received by lens",(P)"Radius of aperture"(R)),((B)"Angular magnification",(Q)"Dispersion of lens"),((C)"Length of telescope",(R)"focal length"f_(0),f_(e)),((D)"Sharpeness of image",(S)"spherical aberration"):}`
Answer» Correct Answer - (A)P;(B)R;(C )R;(D)P,Q,S`

Discussion

375.	Refractive index of glass with respect to water is (9/8). Refractive index of glass with respect to air is (3/2). Find the refractive index of water with respect to air
Answer» Given, `""_(w)mu_(g)=9/8 and ""_(a)mu_(g)=3//2` `As, ""_(a)mu_(g)xx""_(g)mu_(w)xx""_(w)mu_(a)=1` `therefore 1/""_(w)mu_(a)=""_(a)mu_(w)=""_(a)_mu_(g)xx""_(g)mu_(w)=(""_(a)mu_(g))/(""_(a)mu_(g))` `therefore` Refractive index of water with respect to air, `""_(a)mu_(w)=(3//2)/(9//8)=4/3`

Discussion

376.	A printed page is kept pressed by a glass cube (µ=1.5) of edge 9.0 cm. By what amount will the printed letters appear to be shifted when viewed from the top?
Answer» The thickness of the cube=t=9.0 cm. The shift in the position in the printed letter is `Deltad=(1-1/u)d=(1-1.5)xx9.0cm=3.0cm`

Discussion

377.	Assertion : In optical fibre, the diameter of the core is kept small. Reason : The small diameter of the core ensures that the fibre should have inside it an angle greater than critical angle needed for total internal reflection.A. If both, Assertion and Reason are true and the Reason is the correct explanation of the Assertion.B. If both, Assertion and Reason are true but Reason is not a correct explanation of the Assertion.C. If Assertion is true but the Reason is false.D. If both, Assertion and Reason are false.
Answer» Correct Answer - A Both, the Assertion and Reason are true and latter explains the former correctly. Total internal reflection of light takes place if angle of incidence is greater than critical angle. So, small diameter ensures that incident light falls at an angle greater than critical angle.

Discussion

378.	A mark at the bottom of a liquid appears to rise by `0.1m`. The depth of the liquid is `1m`. The refractive index of the liquid isA. 1.33B. `9/10`C. `10/9`D. 1.5
Answer» Correct Answer - c

Discussion

379.	When light is refracted from air into glassA. Its wavelength and frequency both increaseB. Its wavelength increases but frequency remains unchangedC. Its wavelength decreases but frequency remains unchangedD. Its wavelength and frequency both decrease
Answer» Correct Answer - c

Discussion

380.	When light is refracted from air into glassA. Its wavelength and frequency both increase B. Its wavelength increases but frequency remains unchangedC. Its wavelength decreases but frequency remains unchangedD. Its wavelength and frequency both decrease
Answer» Correct Answer - c

Discussion

381.	The distance travelled by light in glass (refractive index =1.5) in a nanosecond will beA. 45 cmB. 40 cmC. 30 cmD. 20 cm
Answer» Correct Answer - d

Discussion

382.	A prism has refractive index `sqrt((3)/(2))` and refractive angle `90^@`. Find the minimum deviation produced by prismA. `40^(@)`B. `45^(@)`C. `30^(@)`D. `49^(@)`
Answer» Correct Answer - C `mu=(sin (delta_(m)+A)//2)/(sinA//2)` `sqrt(3)/(2)=mu=(sin (delta_(m)+A)//2)/(sin45^(@))` `sqrt(3)/(2)xx(1)/(sqrt(2))=sin(delta_m+A)//2 rArr(sqrt(3))/(2)=sin(delta_(m)+A)//2` `sin60^(@)=sin(delta_m+A)//2 rArr delta_(m)+A=120^(@)` `delta_(m) = 30^(@)`

Discussion

383.	In the above problem,If the size of the image formed at the positions are`6cm and 3cm` then the height of the object isA. `4.2cm`B. `4.5cm`C. `5cm`D. None of these
Answer» Correct Answer - A From displacement method `h=sqrt(h_(1)xxh_(2)) implies h= sqrt(6xx3) implies h=sqrt18=4.2"cm"`

Discussion

384.	The focal length of the objective of a terrestrial telescope is 80 cm and it is adjusted for parallel rays, then its magnifying power is 20. If the focal length of erecting lens is 20 cm , then full length of telescope will beA. 84 cmB. 100 cmC. 124 cmD. 164 cm
Answer» Correct Answer - D (d) For terrestrial telescope magnification, `M=f_(o)/(f_(e))=80/(f_(e))=20` `rArr f_(e)=4 cm` Hence, length of terrestrial telescope =`f_(o)+f_(e)+4f` `=80+4+4xx20` =164 cm

Discussion

385.	When a telescope is adjusted for parallel light, the distance of the objective from the eye piece is found to be `80 cm`. The magnifying power of the telescope is 19 . The focal length of the lenses areA. 61 cm , 19 cmB. 40 cm , 40 cmC. 76 cm , 4 cmD. 50 cm , 30 cm
Answer» Correct Answer - c

Discussion

386.	The focal length of the objective of a terrestrial telescope is 80 cm and it is adjusted for parallel rays, then its magnifying power is 20. If the focal length of erecting lens is 20 cm , then full length of telescope will beA. `84 cm`B. `100 cm`C. `124 cm`D. `164 cm`
Answer» Correct Answer - d

Discussion

387.	A telescope has an objective lens of `10cm` diameter and is situated at a distance of one kilometre from two objects. The minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is `5000 Å`, of the order ofA. 5 mmB. 5 cmC. 2.5 mD. 5 m
Answer» Correct Answer - A Here, `D = 10 cm, x = 1 km = 10^5 cm` Distance between two objects, `d = ?` `lamda = 5000 Å = 5 xx 10^-5 cm` Limit of resolution `d theta = (d)/(x) = (lamda)/(D)` `:. d = (x lamda)/(D) = (10^5 xx 5 xx 10^-5)/(10) = 0.5 cm = 5 mm`.

Discussion

388.	We wish to see inside an atom. Assuming the atom to have a diameter of `100` pm, this means that one must be able to resolve a width of say `10` pm. If an electron microscope is used, the minimum electron energy required is aboutA. `1.5 KeV`B. `15 KeV`C. `150 KeV`D. `1.5 KeV`
Answer» Correct Answer - b

Discussion

389.	The focal length of objective and eye lens of a astronomical telescope are respectively `2m` and `5 cm` . Final image is formed at `(i)` least distance of distinct vision `(ii)` infinity. The magnifying power in both cases will beA. `– 48, – 40`B. `– 40, – 48`C. `– 40, 48`D. `– 48, 40 `
Answer» Correct Answer - a

Discussion

390.	A telescope has an objective lens of `10cm` diameter and is situated at a distance of one kilometre from two objects. The minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is `5000 Å`, of the order ofA. 0.5 mB. 5 mC. 5 mmD. 5 cm
Answer» Correct Answer - C

Discussion

391.	Which of the following statement is correct for hypometeropia?A. Near object are not clearly visibleB. Distant object are not clearly visibleC. Concave lens is used for remedy of hypermetropiaD. None of these
Answer» Correct Answer - A (a) In all case of hypermetropia, eye can see distant objects clearly but nearer objects are not clearly visible.

Discussion

392.	Circular part in the centre of retina is calledA. Blind spotB. Yellow spotC. Red spotD. None of the above
Answer» Correct Answer - b

Discussion

393.	Substance on the choroid isA. Japan blackB. Nigrim pigmentC. Carbon blackD. Platinum black
Answer» Correct Answer - b

Discussion

394.	A person is suffering from the defect astigmatism. Its main reason isA. cannot see any objectB. cannot see any object in two perpendicular directions simuletaeouslyC. cannot see near by objectsD. cannot see distant objects
Answer» Correct Answer - B (b) A person suffering from the defect astigmatism cannot see object in two perpendicular directions simultaneously.

Discussion

395.	Two lenses have focal lengths `f_(1)` and `f_(2)` and their dispersive powers are `omega_(1)` and `omega_(2)` respectively. They will together form an achromatic combination ifA. `omega_(1)f_(1)=omega_(2)f_(2)`B. `omega_(1)f_(2)+omega_(2)f_(1)=0`C. `omega_(1)+f_(1)=omega_(2)+f_(2)`D. `omega_(1)-f_(1)=omega_(2)-f_(2)`
Answer» Correct Answer - b

Discussion

396.	Presbyopia can be removed by usingA. convex lensB. concave lensC. cylindrical lensD. bifocal lens
Answer» Correct Answer - D (d) Presbyopia can be removed by using bifocal lens.

Discussion

397.	Two lenses have focal lengths `f_(1)` and `f_(2)` and their dispersive powers are `omega_(1)` and `omega_(2)` respectively. They will together form an achromatic combination ifA. `omega_(1)=2omega_(2) and f_(1)=2f_(2)`B. `2omega_(1)=omega_(2) and f_(1)=2f_(2)`C. `omega_(1)=2omega_(2) and f_(1)=-2f_(2)`D. `2omega_(1)=omega_(2) and 2f_(1)=f_(2)`
Answer» Correct Answer - C (c ) Coordinate of achromatic combination is satisfied, if `omega_(1)/(f_(1))+omega_(2)/(f_(2))=0`

Discussion

398.	The path of a refracted ray of light in a prism is parallel to the base of the prism only when theA. Light is of a particular wavelengthB. Ray is incident normally at one faceC. Ray undergoes minimum deviationD. Prism is made of a particular type of glass
Answer» Correct Answer - c

Discussion

399.	Line spectra are due toA. Hot solidsB. Atoms in gaseous stateC. Molecules in gaseous stateD. Liquid at low temperature
Answer» Correct Answer - b

Discussion

400.	Two light sources of intensities 8 cd and 12 cd are placed on the same side of a photometer screen at a distance of 40 cm from it. Where should a 80 cd source be placed to balance the illuminance ?
Answer» Correct Answer - 80 cm

Discussion

Explore topic-wise InterviewSolutions in .

A convex mirror is used to form the image of an object. Which of the following statements is wrong ?A. The image lies between the pole and the focusB. The image is diminished in sizeC. The image is erectD. The image is real

A horizontal ray of light passes through a prism whose apex angle is `4^@` and then strikes a vertical mirror M as shown in Figure. For the ray to become horizontal after reflection, Find the angle by which the mirror must be rotated. A. `2^(@)`B. `3^(@)`C. `4^(@)`D. `1^(@)`

An object is placed 40 cm from a concave mirror of focal length 20 cm. The image formed isA. real,inverted and same in sizeB. real,inverted and smaller in sizeC. virtual,erect and larger in sizeD. virtual,erect and smaller in size

An object 0.04 m high is placed at a distance of 0.8 m from a concave mirror of radius of curvature 0.4 m. find the position, nature and the size of the image formed.

An object 5 cm tall is placed 1 m from a concave spherical mirror which has a radius of curvature of 20 cm. The size of the image isA. 0.11 cmB. 0.5 cmC. 0.55 cmD. 0.60 cm

A virtual image three times the size of the object is obtained with a concave mirror of radius of curvature 36cm. The distance of the object from the mirror isA. 5 cmB. 12 cmC. 10 cmD. 20 cm

For a real object, which of the following can produced a real imageA. Plane mirrorB. Concave lensC. Convex mirrorD. Concave mirror

A plane mirror reflects a pencil of light to form a real image. Then the pencil of light incident on the mirror isA. ParallelB. ConvergentC. DivergentD. None of the above

Two vertical plane mirrors are inclined at an angle of `60^(@)` with each other. A ray of light travelling horizontally is reflected first from one mirror and then from the other. The resultant deviation isA. `60^(@)`B. `120^(@)`C. `180^(@)`D. `240^(@)`

A convax lens of focal length `10.0cm`is placed in contact with a convex lens of `15.0cm` focal length ,What is the focal length of the combination.

An object is placed at a distant of `1.50` from a screen and a convex lens placed in between produces an image magnified `4`times on the screen .What is the focal length and the position of the lens.

If two lenses of `+5` dioptres are mounted at some distance apart, the equivalent power will always be negative if the distance isA. Greater than 40 cmB. Equal to 40 cmC. Equal to 10 cmD. Less than 10 cm

When a glass slab is placed on a cross made on a sheet, the cross appears to be raised by `1cm`. The thickness of the glass is `3cm`. The critical angle for glass isA. `sin^(-1)(0.33)`B. `sin^(-1)(0.5)`C. `sin^(-1)(0.67)`D. `sin^(-1)((sqrt(3))/2)`

A convex lens produces a real image `m` times the size of the object. What will be the distance of the object from the lens ?A. `((m+1)/(m)) f`B. `( m – 1 ) f `C. `((m-1)/(m))f`D. `(m+1)/(f)`

A convex lens is made up of three different materials as shown in the figure. For a point object placed on its axis, the number of images formed are A. 1B. 5C. 4D. 3

A layered lens is made of materials indicated by shades in the figure. The number of images formed is A. 1B. 2C. 3D. 4

Total flux produced by a source of `1 cd ` isA. `(1)/(4pi)`B. `8 pi`C. `4pi`D. `(1)/(8pi)`

Refractive index of glass with respect to water is (9/8). Refractive index of glass with respect to air is (3/2). Find the refractive index of water with respect to air

A printed page is kept pressed by a glass cube (µ=1.5) of edge 9.0 cm. By what amount will the printed letters appear to be shifted when viewed from the top?

A mark at the bottom of a liquid appears to rise by `0.1m`. The depth of the liquid is `1m`. The refractive index of the liquid isA. 1.33B. `9/10`C. `10/9`D. 1.5

When light is refracted from air into glassA. Its wavelength and frequency both increaseB. Its wavelength increases but frequency remains unchangedC. Its wavelength decreases but frequency remains unchangedD. Its wavelength and frequency both decrease

When light is refracted from air into glassA. Its wavelength and frequency both increase B. Its wavelength increases but frequency remains unchangedC. Its wavelength decreases but frequency remains unchangedD. Its wavelength and frequency both decrease

The distance travelled by light in glass (refractive index =1.5) in a nanosecond will beA. 45 cmB. 40 cmC. 30 cmD. 20 cm

A prism has refractive index `sqrt((3)/(2))` and refractive angle `90^@`. Find the minimum deviation produced by prismA. `40^(@)`B. `45^(@)`C. `30^(@)`D. `49^(@)`

In the above problem,If the size of the image formed at the positions are`6cm and 3cm` then the height of the object isA. `4.2cm`B. `4.5cm`C. `5cm`D. None of these

The focal length of the objective of a terrestrial telescope is 80 cm and it is adjusted for parallel rays, then its magnifying power is 20. If the focal length of erecting lens is 20 cm , then full length of telescope will beA. 84 cmB. 100 cmC. 124 cmD. 164 cm

When a telescope is adjusted for parallel light, the distance of the objective from the eye piece is found to be `80 cm`. The magnifying power of the telescope is 19 . The focal length of the lenses areA. 61 cm , 19 cmB. 40 cm , 40 cmC. 76 cm , 4 cmD. 50 cm , 30 cm

The focal length of the objective of a terrestrial telescope is 80 cm and it is adjusted for parallel rays, then its magnifying power is 20. If the focal length of erecting lens is 20 cm , then full length of telescope will beA. `84 cm`B. `100 cm`C. `124 cm`D. `164 cm`

A telescope has an objective lens of `10cm` diameter and is situated at a distance of one kilometre from two objects. The minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is `5000 Å`, of the order ofA. 5 mmB. 5 cmC. 2.5 mD. 5 m

We wish to see inside an atom. Assuming the atom to have a diameter of `100` pm, this means that one must be able to resolve a width of say `10` pm. If an electron microscope is used, the minimum electron energy required is aboutA. `1.5 KeV`B. `15 KeV`C. `150 KeV`D. `1.5 KeV`

The focal length of objective and eye lens of a astronomical telescope are respectively `2m` and `5 cm` . Final image is formed at `(i)` least distance of distinct vision `(ii)` infinity. The magnifying power in both cases will beA. `– 48, – 40`B. `– 40, – 48`C. `– 40, 48`D. `– 48, 40 `

A telescope has an objective lens of `10cm` diameter and is situated at a distance of one kilometre from two objects. The minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is `5000 Å`, of the order ofA. 0.5 mB. 5 mC. 5 mmD. 5 cm

Which of the following statement is correct for hypometeropia?A. Near object are not clearly visibleB. Distant object are not clearly visibleC. Concave lens is used for remedy of hypermetropiaD. None of these

Circular part in the centre of retina is calledA. Blind spotB. Yellow spotC. Red spotD. None of the above

Substance on the choroid isA. Japan blackB. Nigrim pigmentC. Carbon blackD. Platinum black

A person is suffering from the defect astigmatism. Its main reason isA. cannot see any objectB. cannot see any object in two perpendicular directions simuletaeouslyC. cannot see near by objectsD. cannot see distant objects

Presbyopia can be removed by usingA. convex lensB. concave lensC. cylindrical lensD. bifocal lens

The path of a refracted ray of light in a prism is parallel to the base of the prism only when theA. Light is of a particular wavelengthB. Ray is incident normally at one faceC. Ray undergoes minimum deviationD. Prism is made of a particular type of glass

Line spectra are due toA. Hot solidsB. Atoms in gaseous stateC. Molecules in gaseous stateD. Liquid at low temperature

Two light sources of intensities 8 cd and 12 cd are placed on the same side of a photometer screen at a distance of 40 cm from it. Where should a 80 cd source be placed to balance the illuminance ?