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