5th Class Science Lights, Sound and Force Shadow formation

          Shadow Formation  

Shadow is formed when opaque objects come in between light source and the screen (Which can be ground, wall etc.).

Light always casts shadows of the opaque objects placed in its path. The size and direction of the shadow depend on the direction and distance of the light coming from the source.

Shadow formation reveals that light always travels in a straight line and the portion through which light can't pass through becomes dark, which is called shadow. The direction of light source affects the direction of shadow formation.

Shadows are always black and represent the outline of the object.

Conditions necessary for the formation of shadow:

Source of light

An opaque object.

Screen on which shadow is formed.

           Human Eye and Light

Organ in the body which receives light sensation are eyes.

Look at the following picture of internal structure of eye:

Internal structure of eye

Look at the following picture of parts of eyes and their functions:

      Shruti is surprised to see the light phenomena in National Science Centre where the different types of images of a person are seen in a mirror. Which branch of science she should study to understand the reason behind this?

(a) Acoustic

(b) Optics

(c) Zoology

(d) Astronomy

(e) Botany

Answer: (b)

Explanation

Number of images formed would depend on the angle between the mirrors, infinite images are formed when two mirrors are placed parallel to each other. Therefore, option (B) is correct and rest of the options is incorrect.

      Dimpy and Ashoo are talking about the given natural phenomena. Who is correct Dimpy or Ashoo?  

Thunder storm and lightening

(a) Dimpy

(b) Ashoo

(c) Both are correct

(b) Both are incorrect

(e) None of these

Answer: (b)

Explanation

Speed of light is faster than the speed of sound, hence lightening is seen first than thunderstorm. Therefore, option (B) is correct and

rest of the options is incorrect.