Extra Explaining Question - LIGHT

LIGHT

1. 1.

   Imagine you are looking your face using a plane mirror, note out five characteristics of your face image.

   1. Same size as object
   2. Virtual image
   3. Laterally inverted
   4. Erect
   5. Same distance behind mirror
2. 2.

   Briefly explain three evidences to show concave mirrors are useful in daily life.

   1. Used in shaving mirrors
   2. Used in car headlights
   3. Used by dentists for magnification
3. 3.

   Why do different colours of light refract through different angles in a prism?

   Different colours have different wavelengths and travel at different speeds in glass, causing dispersion.
4. 4.

   By the aid of diagram, state procedures for measuring refractive index of water using apparent depth method.

   Measure real depth and apparent depth then compute refractive index = real depth ÷ apparent depth.
5. 5.

   Explain why a red flower looks red when seen in white light.

   It reflects red light and absorbs other colours.
6. 6.

   What colour does a red flower appear to be when seen in:
   i) Red light
   ii) Green light

   1. Red light → Red
   2. Green light → Black
7. 7.

   Explain why water in a swimming pool appears shallower than it really is.

   Due to refraction of light at the water-air boundary.
8. 8.

   Why does the sky appear blue from Earth and black when viewed from the Moon?

   Earth has atmosphere that scatters sunlight while the Moon has no atmosphere.
9. 9.

   Briefly explain two ways of combining spectrum colours into white light.

   Newton’s disc and additive colour mixing.
10. 10.

    Briefly explain two conditions for total internal reflection.

    Light must travel from denser to rarer medium and angle of incidence must exceed critical angle.