Science Class 8th

321. A lens which is thin at the middle and thicker at the edge is called ____ lens

A) Concave

B) Convex

C) Converging lens

D) None of the above

322. Concave lens is also called _____ lens

A) Converging

B) Diverging

C) Sub diverging

D) None of the above

323. Centre of the sphere of which the curved surface of the lens is a part is called ____

A) Centre of curvature

B) Centre of converging

C) Centre of diverging

D) None of the above

324. The central point of a lens is called ____ point.

A) Optical

B) None optical

C) Upper

D) None of the these

325. The distance between optical centre and principal focus is called ______ A

A) Focal length

B) Optical length

C) Converging length

D) None of these

326. The iris diaphragm has a ____in the middle of the eye which controls the amount of light going into the eyes.

A) Retina

B) Cornea

C) Pupil

D) None of the above

327. _____ control the pupil size.

A) Iris

B) Retina

C) Cornea

D) None of the above

328. The ____ acts like a screen on which inverted image is formed.

A) Retina

B) Cornea

C) Pupil

D) None of the above

329. The ______ carries image from the retina to the brain.

A) Optic nerve

B) Retina

C) Cornea

D) None of the above

330. A person suffering from _______ cannot see far off objects.

A. Long  sightedness

B. Short Sightedness

C. Both a & b

D. None

331. The lens of short sightedness become _____

A) Thin  

B) Thick  

C) Weak  

D) Strong 

332. The focal length of short sightedness ____

A) Increases

B) Reduced

C) Option B is correct

333. Short sightedness can be corrected by wearing spectacles having _____ lens.

A) Convex

B) Concave

C) Optical

D) None of the above

334. A person suffering from _______ cannot see the near objects

A. Long Sightedness

B. Short Sightedness

C. Both  a & b

D. None

335. Long sightedness can be removed by wearing spectacles having ____ lens.

A) Concave

B) Convex

C) Focal

D) None of the above

336. Cone cell can perceive colour in ____ light.

A) Dark

B) Bright

C) Dim

D) Day

337. Rod cells perceive black and _____ images.

A) Red

B) Yellow

C) White

D) None of these

338. When you move from dark light to bright the cone cells are deactivated.

A) True

B) False

339. A ray parallel to principal axis, after refraction from convex lens:

A) Does not bend

B) Passes through centre of curvature

C) Passes through principal focus

D) Passes through the centre of lens.

340. The image formed by a concave lens is always _____

A) Virtual

B) Red

C) Inverted

D) Larger