CBSE X The Human Eye and the Colourful World practice questions

Question 1

Assertion (A): A person with myopia typically sees near objects clearly but distant objects poorly.
Reason (R): An elongated eyeball can cause distant images to focus in front of the retina.

Accepted Answer

Both A and R are true and R explains A.

Answer

Both A and R are true but R does not explain A.

Answer

A is true but R is false.

Answer

A is false but R is true.

Question 2

What is the Tyndall effect?

Accepted Answer

Visible scattering of light by particles in a colloidal or suitably suspended medium

Answer

Splitting a heavy atomic nucleus

Answer

Production of electric current by chemical reactions

Answer

Only reflection from a perfectly smooth mirror

Question 3

Why would a daytime sky appear dark from a location with no atmosphere,apart from visible light sources?

Accepted Answer

There is no atmosphere to scatter sunlight into the viewing direction

Answer

The Sun emits no light there

Answer

Every star stops emitting light

Answer

A vacuum produces a blue pigment

Question 4

What is the spectrum produced when a prism disperses white light?

Accepted Answer

The band of component colours

Answer

Only one colourless dot in every case

Answer

A list of eye muscles

Answer

A magnetic-field diagram

Question 5

When is the eye lens’s focal length generally longer in normal accommodation?

Accepted Answer

When ciliary muscles are relaxed for distant viewing

Answer

When the lens is made thicker for near viewing

Answer

When the eye must focus closer objects with greater lens power

Answer

Focal length can never change

Question 6

What is scattering of light?

Accepted Answer

Redistribution of light into different directions through interaction with matter

Answer

Only permanent disappearance of all photons without interaction

Answer

Only bending at one ideal smooth refracting boundary

Answer

Only making an electric current

Question 7

In a school myopia model,a student has difficulty seeing writing 5 m away. Where does the uncorrected distant-object focus tend to form?

Accepted Answer

In front of the retina

Answer

Behind the retina as the defining myopia focus

Answer

Only on the cornea

Answer

Only outside the eye before entry

Question 8

Which pair of optical factors can contribute to myopia?

Accepted Answer

An elongated eyeball or excessive converging power relative to its length

Answer

Only an eye too short for its focusing power

Answer

Only an absence of every refracting surface

Answer

Only a change in eyebrow colour