Light, Shadows and Reflections

Q1. Fill in the blanks.

                          i.        The sun is a natural source of light.

                         ii.        Light is a form of energy.

                        iii.        A shadow is black in color.

                        iv.        Candles, oil lamps and earthen lamps are man-made sources of light.

                         v.        An image has the color of the object.

                        vi.        A highly polished furniture acts like a mirror.

Q2. True/False

                          i.        Any non-luminous body can be made luminous by heating it. True

                         ii.        Any material through which light energy pass partially or wholly is called an opaque object. False

                        iii.        A cardboard is an example of an opaque object. True

                        iv.        A glass is a transparent object. True

                         v.        A shadow is colorful. False

Q3. What is light?

Ans. Light is form of energy which excites the sensation of vision.

Q4. Is moon a luminous or non-luminous body?

Ans. Moon is a non-luminous body.

 
Q5. How does light travel?

Ans. Light travels in a straight line.

Q6. Write one property of light.

Ans. Light travels in a straight line.

Q7. Name one living thing which emits light?

Ans. Jugnu (firefly)

Q8. What could be the shape of the shadows?

Ans. It will similar to the object.

Q9. Does the color of opaque object affect the color of the shadow?

Ans. No, the color of opaque object does not affect the color of the shadow.

Q10. When shadow cannot be formed?

Ans. Shadow cannot be formed when light is coming from all direction.

Q11. Does the flame of gas stove emit light? Explain.

Ans. Yes, the flame of gas stove emits light because it is visible in the dark.

Q12. Can light pass through opaque objects?

Ans. No, light cannot pass through opaque objects.

Q13. Can we see shadow even if there is no light?

Ans. No, we cannot see shadow in the absence of light.

Q14. What is the color of a shadow?

Ans. A shadow is black in color.

Q15. How can non-luminous object be made luminous?

Ans. Non-luminous object can be made luminous by heating it.

Q16. Why does a pinhole camera produces an inverted (upside down) image?

Ans. A pinhole camera produces an inverted image because light travels in straight line.

Q17. What do you understand by rectilinear propagation of light?

Ans.  The light travels in straight line. This phenomenon is called the rectilinear propagation of light.

 
Q18. When we are able to see the object?

Ans. We are able to see the object when reflected light from the object enters our eyes.

Q19. What is a reflector? Give one example.

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

Q20. Why polished surfaces causes glare in our eyes?

Ans. Polished surface produces regular reflections which causes glare in our eyes.

Q21. Write some natural sources of light.

Ans. Some natural sources of light are the sun, the moon, the stars and the glowworm or firefly or Jugnu.