Advertisements
Advertisements
प्रश्न
Explain briefly what causes the twinkling of stars at night.
Advertisements
उत्तर
Stars are very far from us. The light ray coming from a star undergoes successive refractions on entering the earth’s atmosphere and bends towards the normal. Hence, an apparent image of the star is seen. Simultaneously due to the movement of air, the refractive index of layers of atmosphere keeps on changing, i.e., the apparent position of star keeps changing. Thus, the star appears to twinkle.
संबंधित प्रश्न
Name one factor that affects the lateral displacement of light as it passes through a rectangular glass slab.
A ray of light passes from water to air. How does the speed of light change?
Light passes through a rectangular glass slab and through a triangular glass prism. In what way does the direction of the two emergent beams differ and why?
With the help of diagram of the principal section of a prism, indicate its refracting surfaces, refracting edge and base.
Light of a single colour is passed through a liquid having a piece of glass suspended in it. On changing the temperature of liquid, at a particular temperature, the glass piece is not seen.
Why is the light of a single colour used ?
Choose the correct alternative and rewrite the following:
A glass slab is placed in the path of convergent light. The point of convergence of light
Does the depth of a tank of water appear to change or remain the same when viewed normally from above?
Trace a ray of light incident at 30° on a surface if travelling from glass to air. What is the angle of refraction in this case? (R.I. for glass = 3/2).
Write the approximate values of speed of light in (i) air and (ii) glass. Use these values to calculate the refractive index of glass with respect to air.
What is lateral displacement?
