CONCEPT:
- Refraction of Light: The bending of the ray of light passing from one medium to the other medium is called refraction.
- The refraction of light takes place on going from one medium to another because the speed of light is different in the two media.
- The greater the difference in the speeds of light in the two media, the greater will be the amount of refraction.
- A medium in which the speed of light is more is known as an optically rarer medium and a medium in which the speed of light is less is known as an optically denser medium.
EXPLANATION:
- Since the frequency of any light wave depends on the source frequency. Frequency doesn't depend on the medium.
- So whenever the light goes from one medium to another or vice versa, the frequency of light and phase of light do not change. Therefore the option 4 is correct.
- However, the velocity of light, the wavelength of light, and intensity depend on the medium, and hence the change.
- Hence, when light waves are incident on an air-glass boundary, then the speed, direction, and brightness of the light wave changes.
Therefore options 1,2 , and 3 are incorrect.
- In fig b we can see sin component of mg will be responsible for bringing the pendulum back to its original position, thus in case of a simple pendulum the restoring force acting on it can be expressed as
⇒f=mgsinθ⇒f∝θ (if
sinθ is very small and
mg are constant)
Here,
f= restoring force and
x= displacement and
k are proportionality constant.
EXPLANATION:
- From above it is clear that the restoring force is proportional to the displacement of the body in simple harmonic motion. Therefore option 3 is correct.