## Science – Light, Refraction and Dispersion - Assignment

Q1: What do you mean by refraction of light? In which direction will light bend when travelling from an optically rarer medium to an optically denser medium?

Q2: Name the part of the eye which gives colour to the eyes.

Q3: Boojho while waving his hand very fast in front of his eyes, observes that his fingers appear blurred. What could be the reason for it?

Q4: How many times is a ray of light reflected by two plane mirrors placed parallel and facing each other?

Q5: Why does refraction occur?

Q6: What is dispersion?

Q7: Which medium will bend light more—glass or water? Why?

Q8: What is the order of colours in a spectrum of 'white light'?

Q9: Distinguish between near point and far point of the eye.

Q10: What is the 'blind spot' of the eye?

Q11: The angle between incident ray and reflected ray is 60°. What is the value of angle of incidence?

Q12: What kind of lens is there in our eyes? Where does it form the image of an object?

Q13: Explain the process which enables us to perceive motion in a cartoon film.

Q14: Write down the names of parts of the eye in the blank spaces shown in Figure

Q15: What is the difference between the displacement produced by a rectangular glass slab in a ray of light and the deviation produced by a glass prism?

Q16: Distinguish between converging and diverging lenses.

Q17: Define the following terms for a lens:

a. optical centre
b. principal axis
c. principal focus
d. focal length

Q18: What is meant by 'persistence of vision'? How is this property of the eye used in movie films?

Q19: A coin kept at the bottom of a glass bowl full of water appears to be higher than it actually is. With the help of a labelled diagram, explain why this happens.

Q20: As an object is slowly brought from infinity to the focus of a convex lens, the image travels from the focus to infinity.' Show this with the help of diagrams with five different positions of the object.

Q21: Distinguish between myopia and hypermetropia. Draw diagrams to show how these defects can be corrected by using suitable lenses.

Q22: Can a glass slab bend different coloured lights by different amounts?

Q23: Give one word for the following:

1. The invisible energy which causes in use the sensation of vision.
2. The ray of light which travels towards a mirror.
3. A line which is drawn at right angles to the mirror surface at the point of incidence.
4. Name one type of mirror which always form virtual image.
5. What type of image is formed on the cinema screen ?
6. Which cells on the retina respond to the intensity of light.
7. The part of the eye which preserves its shape and protects it from external injuries.
8. The phenomenon due to which we can judge depth.
9. The most sensitive part of the retina.