When the two surfaces of a thin film are parallel and the light is incident at some angle what fringes are formed? A. Circular B. Elliptical C. Parabolic D. Straight and why?

The correct option is;

A. Circular

Explanation:

Some of the light that impinges on the surface are reflected and the rest are transmitted to a different medium

At the surface of the next medium also, some of the light are transmitted while the others are reflected and refracted through the first medium

The speed of light (and hence the wavelength and color) refracted through the thin film is changed as the distance the refracted light travels through the thin film is increased as we move away from the point directly in the front view to some distance as the reflected light path from those distance to the eye is increased due to their inclination giving them a different wavelength which are all equal at a radial distance from the eye hence forming a circular fringes.

radiation

explanation:

heat is transmitted by radiation

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.