Tag: light and shadow

Questions Related to light and shadow

A ray of sunlight enters a spherical water droplet $(n = \dfrac{4}{3})$ at an angle of incidence $53^\circ$ measured with respect to the normal to the surface. It is reflected from the back surface of the droplet and re-enters into air. The angle between the incoming and outgoing ray is [Take $\sin \ 53^\circ = 0.8$]

physics light and shadow formation of image by a pinhole camera pinhole camera shadow

  1. $15^\circ$

  2. $127^\circ$

  3. $138^\circ$

  4. $30^\circ$

Show answer
Correct Option: B
Explanation:

The angle between the incoming and outgoing ray is $180^o-53=127$.

A small plane mirror kept at the centre of a sphere of diameter $3\ m$, makes $12$ revolution per second. A thin light beam is made incident on the mirror. The linear speed of the light spot on the sphere, formed after reflection from the mirror is :

physics light and shadow formation of image by a pinhole camera pinhole camera shadow

  1. $18\pi\ m/s$

  2. $36\pi\ m/s$

  3. $72\pi\ m/s$

  4. $144\pi\ m/s$

Show answer
Correct Option: D
Explanation:

When plane mirror rotates through an angle $\theta$ , the reflected ray rotates through an angle 2$\theta$. So spot on the screen will make 2 x 12 = 24  revolution per second.

 
To find the velocity 
v=2$\pi$R x frequency 
=2$\pi$ x 3 x 24
=144$\pi$ m/s

 D is the Correct answer.
 

Intensity of light due to a point source at a distance $2m$ is $20$ units. The intensity due to the same source at a distance of $4m$ is

physics light and shadow formation of image by a pinhole camera pinhole camera shadow

  1. $2.5\ units$

  2. $6\ units$

  3. $80\ units$

  4. $5\ units$

Show answer
Correct Option: D

Light has a wave nature,because-

physics light and shadow formation of image by a pinhole camera pinhole camera shadow

  1. The light travel in a straight line

  2. Light exhibits phenomenon of reflection and refraction

  3. Lights phenomeno interference

  4. Light exhibits phenomeno of photo electric effect

Show answer
Correct Option: C

Which one statement is correct -

physics light and shadow formation of image by a pinhole camera pinhole camera shadow

  1. Speed of light in free space $= \frac{1}{\sqrt{\mu _0 \varepsilon _0}}$

  2. Speed of light in any medium $=\frac{1}{\sqrt{\mu \varepsilon}}$

  3. $\frac{E _0}{B _0}=2C$

  4. $\frac{B _0}{E _0}=4C$

Show answer
Correct Option: A

Light falls on a plane reflecting surface. For what angle of incidence is the reflected ray normal to the incident ray. 

physics light and shadow formation of image by a pinhole camera pinhole camera shadow

  1. $60^o$

  2. $45^o$

  3. $90^o$

  4. $30^o$

Show answer
Correct Option: D
Explanation:

The incident ray will have an angle of reflection of ${30^0}$ $($made with a surface normal to the mirror surface$).$

Hence,
option $(D)$ is correct answer.

The speed of light in air is ___________ m/s.

physics light and shadow formation of image by a pinhole camera pinhole camera shadow

  1. $3$

  2. $3\times { 10 }^{ -5 }$

  3. $3\times { 10 }^{ 8 }$

  4. $3\times { 10 }^{ 10 }$

Show answer
Correct Option: C

The colour of a green leaf, when white light passing through a yellow filter is applied on it is:

evs light and shadow nature and sources of light how light travels path of light elementary ideas of astronomy

  1. black

  2. yellow

  3. red

  4. green

Show answer
Correct Option: A
Explanation:

A yellow filter allows only yellow colour to pass through it. A leaf looks green because leaf reflects green colour and absorbs the rest. Thus, the yellow light passing through the filter will be absorbed by the green leaf. Thus, no colour will be reflected by the leaf making it appear black.

The path along which light travels is called a ........

evs light and shadow nature and sources of light how light travels path of light elementary ideas of astronomy

  1. ray

  2. line

  3. line segment

  4. none

Show answer
Correct Option: A
Explanation:

The path along which light travels is called a Ray.

A beam of light gets reflected from a plane mirror and a real image is formed. The incident beam should be 

evs light and shadow nature and sources of light how light travels path of light elementary ideas of astronomy

  1. Parallel

  2. Convergent

  3. Divergent

  4. Plane mirror cannot form a real image

Show answer
Correct Option: B
Explanation:

  1. Plane mirrors don't usually form real images They form virtual images of real objects. However, things can be arranged so that a plane mirror does form a real image. A convergent light beam can do this. So the answer is "convergent"

  2. When at convergence point, a convergent beam of light is incident on the plane mirror, a real image is formed at the point