Light class 8and 7

What makes objects visible?

• The total internal reflection taking place in an object

• The refracted light from the object

• The absorption of light by objects

• The reflected light from the object

What is the perpendicular drawn at any point on a mirror called?

• A) Incident ray

• B) Reflected ray

• C) Normal

• D) Image

How many images are obtained when plane mirrors are arranged parallel to each other?

• A) A single image

• B) Two images

• C) Infinite number of images

• D) Zero image

In our houses, which of the following is used for looking at ourselves?

• A) Convex mirror

• B) Concave mirror

• C) Convex lens

• D) Plane mirror

In a periscope, how are the reflecting mirrors arranged?

• A) Perpendicular to each other

• B) Parallel to each other

• C) At an angle of 90 degree

• D) At an angle of 60 degree

What is the nature of image formed on the retina of human eye of an object?

• A) Virtual and erect

• B) Virtual and inverted

• C) Real and erect

• D) Real and inverted

Identify the value of persistence of vision.

• A) 1/1 0th of a second

• B) 1/12th of a second

• C) 1/16th of a second

• D) 1/20th of a second

The characteristics of an eye disease are given below.(i) Eye sight becomes foggy(ii) Eye lens becomes cloudy(iii) There is a loss of visionIn which of the following are the above characteristics observed?

• A) Myopia

• B) Presbyopia

• C) Hypermetropia

• D) Cataract

How is a rainbow formed?

• A) When raindrops absorb sunlight

• B) When raindrops reflect sunlight

• C) When raindrops disperse sunlight

• D) When raindrops diffract sunlight

A series of fast moving still pictures can create an illusion of movement. Why?

• A) The eye can focus on very rapidly changing pictures.

• B) The eye is quicker than the brain.

• C) The eye can separate two images only when the interval of separation between them is one-sixteenth of a second.

• D) The optical cortex can see through the rapidly moving images.