Important Question with solution

Q1: Does the flame of a gas stove emit light?

Ans: Yes. 

Q2: What is rectilinear propagation of light?

Ans: Light travels in a straight line.

Q3: Write the names of 4 different sources of light?

Ans: Bulb, sun, stars, firefly

Q4: Give one example of living thing which emits light?

Ans: Jugnu {firefly)

Q5: Sometimes you are able to see sun or moon behind the clouds .What can you say about the ability of such clouds to transmit light?

Ans: Yes, clouds transmit light.

Q6: Image formed in a pinhole camera is inverted .Why?

Ans: It is inverted because of the rectilinear propagation of light.

Q7: Can you suggest the shape of the shadows?

Ans: It is usually similar to the object.

Q8: Does the length of shadow change from season to season?

Ans: Yes if observed at same time .

Q9: Define reflection of light?

Ans: The process of returning/ bouncing back the light to the same medium after Striking a surface is called reflection of light.

Q10: What is a reflector?

Ans: A surface which reflects the light is called reflector.

Q11: What is shadow?

Ans: A dark patch formed behind an opaque object when it is placed in the path of light is called shadow.

Q12: What do you mean by reflection of light?

Ans:Coming back of light ray incident on a surface is called reflection.

Q13: What is the principle of working f a pin hole camera?

Ans: A pinhole camera is based on rectilinear propagation of light?

Q14: Can light pass through opaque objects?

Ans: No

Q15: What is an artificial source of light?

Ans: Man made sources of light. For example: electric bulb, candle etc.

Q16: Classify the following into transparent, translucent, and opaque objects.

Glass, air, oil, oily paper, rubber sheet, polythine, water, football, table

Ans:

Transparent: air, glass, water

Translucent: oil, oily paper, polythine

Opaque: rubber sheet, football, table

Q17: Name two artificial sources of light?

Ans: Electric bulb, candle

Q18: Name one transparent and one opaque body?

Ans: Transparent: air Opaque: stone

Q19: Give one example of most commonly used reflector?

Ans: Looking glass or plane mirror

Q20: Does the reflection of light from the surface similar to the bouncing back of a rubber ball after it strikes from a ball? Explain.

Ans: Yes, because of reflection, light falling on a surface bounces back to the same medium. When a light strikes a surface after the reflection it turns back in the same medium.

Q22: Give the properties of the image formed by the plane mirror?

Ans: The basic properties of plane mirror is as follow; 

(i) The plane mirror alsways forms a virtual and errect image.

(ii) Size of the image formed by plane mirror is equal to the size of the object.