Tag: nature and sources of light

Questions Related to nature and sources of light

The path along which light travels in a homogeneous medium is called a :

  1. beam of light

  2. ray of light

  3. pencil of light

  4. line of light


Correct Option: B
Explanation:

The path along which light travels in a homogeneous medium is called a ray of light

Light waves:

  1. require air or another gas to travel through

  2. require an electric field to travel through

  3. require a magnetic field to travel through

  4. can travel through perfect vacuum


Correct Option: D
Explanation:

Light is an electromagnetic wave which is transverse in nature. It does not require any material medium to pass through and can travel through vacuum.

Which of the following is a non-luminous body ?

  1. Sun

  2. Moon

  3. Candle flame

  4. Electric lamp


Correct Option: B
Explanation:

Moon does not emit its own light. It reflects the light incident on it from the Sun. So, Moon is a non-luminous body.

Find out the only wrong statement in the following:

  1. Light travels with a speed greater than that of sound

  2. Light cannot travel through vacuum

  3. Light travels in a straight line

  4. Light has no weight


Correct Option: B
Explanation:

Light is an electromagnetic wave which is transverse in nature. So, it does not require any material medium to pass through. Light, thus, can travel through vacuum.

A green leaf placed in a dark room is illuminated by red light. The leaf will appear to be :

  1. green

  2. red

  3. yellow

  4. black


Correct Option: D
Explanation:

A green leaf can only reflect green light, so when red light is incident on it, the leaf will not be able to reflect any light making it look black

The path along which light travels in a homogenous medium is called the

  1. beam of light

  2. ray of light

  3. pencil of light

  4. none of these


Correct Option: B
Explanation:

Definition:- The path a traced by light is called a ray of light. 

We can see an object from every direction due to ____________ of the incident light ray on the object.

  1. regular refraction

  2. regular reflection

  3. irregular reflection

  4. none of these


Correct Option: C
Explanation:

Irregular reflection makes us see all the objects and everything around us. If light gets regularly reflected then every object would act like a mirror and our surroundings would be illuminated. This would have a blinding effect on eyes making it harder for us to see.

A leaf which contains only green pigments, is illuminated by a laser light of wave length 0.6328 $\mu$ m. It wound appear to be:

  1. Brown

  2. Black

  3. Red

  4. Green


Correct Option: B
Explanation:

0.6328 $\mu m$ = $6328 \mathring A$
This is wavelength of red colour. So, this light will be absorbed by green pigments. 
The leaf will appear black.

Fill in the blanks:

According to Newton, different colors of light are due to the difference in _______ of the corpuscles.

  1. mass

  2. nature

  3. shape

  4. size


Correct Option: D
Explanation:

Corpuscles are single, infinitesimally small, particles which have shape, size, color, and other physical properties.

Light of wavelength $\lambda $ from a point source falls on a small circular obstacle of diameter d. Dark and bright circular rings around a central bright spot are formed on a screen beyond the obstacle. The distance between the screen and obstacle is D. Then , the condition for the formation of rings, is

  1. $\sqrt { \lambda } \approx \cfrac { { d } }{ 4D } $

  2. $\lambda \approx \cfrac { { d }^{ 2 } }{ 4D } $

  3. $d\approx \cfrac { { \lambda }^{ 2 } }{ D } $

  4. $\lambda \approx \cfrac { D }{ 4 } $


Correct Option: B