Pick the wrong statement in the context with a rainbow.
1. Rainbow is a combined effect of dispersion, refraction, and reflection of sunlight.
2. When the light rays undergo two internal reflections in a water drop, a secondary rainbow is formed.
3. The order of colours is reversed in the secondary rainbow.
4. An observer can see a rainbow when his front is towards the sun.
A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source L. When the mirror is rotated through a small angle , the spot of the light is found to move through a distance y on the scale. The angle is given by:
A tall man, of height 6 feet, wants to see his full image. The required minimum length of the mirror will be:
1. 12 feet
2. 3 feet
3. 6 feet
4. Any length