Light | Chapter Assessment | English | Grade 8

A ray of light, drawn in a ray diagram, is an actual representation of a single ray of light.

• TRUE

• FALSE

Answer explanation

A ray of light is an idealisation. In reality, we have a narrow beam of light which is made up of several rays.

The angle of incidence is measured between

• The normal and the incident ray

• The surface and the incident ray

• The incident ray and the reflected ray

• The normal and the surface

Answer explanation

The angle of incidence is measured between the incident ray and the normal.

Tags

NGSS.MS-PS4-2

The normal makes an angle of ____ from the surface.

• 0

• 45

• 90

• 180

Answer explanation

The normal is defined to be the line that make an angle of 90 degrees from the surface.

Your reflection on a plain mirror is

• Real and Erect

• Virtual and upside Down

• Virtual and Erect

• Real and Upside Down

Answer explanation

The image formed by plane mirrors are virtual and erect. As the image appears to be formed behind the image, it cannot be obtained on a paper, therefore it is virtual. All the images formed by a plain mirror are erect.

Tags

NGSS.MS-PS4-2

On placing two mirrors facing each other and putting an object between them, the number of images formed will be

• 1

• 2

• 100

• Infinite

Answer explanation

Since the two mirrors are placed face to face, the image formed on the first mirror will become an object for the second mirror and vice versa. This will be true for all the images formed, and hence there will be infinite images.

Tags

NGSS.MS-PS4-2

The cells, in the human eye, that senses colour is

• Rods

• Cones

• Optic Nerve

• None of the above

Answer explanation

Cones sense colour. When a person is said to be colour blind, they normally are colour blind to only a handful of colours. This is because some of the cones that sense colour gets damaged.

Humans can see all the objects whose light falls in their eyes.

• TRUE

• FALSE

Answer explanation

Humans see most of the objects whose light it receives, but there is a blindspot. It is located at the junction of the optic nerve and the retina.

Tags

NGSS.MS-PS4-2