Answer. As the lens is lifted the difference in optical path between the two reflected rays will vary, thus slowly converting bright rings to dark and vice versa . This will be periodic change.
What will happen if the lenses slowly lifted off the plate?
(ii) If the lens is lifted slowly off the plate by a distance of half the wavelength, then nth dark ring will shrink to (n-1)th dark ring . Thus, as the distance between the lens and plate is increased the thickness and hence the order of ring at a given point increases.
What is the effect of increasing the distance between plane convex lens and glass plate in Newton’s ring experiment?
When a plano-convex surface is placed on a glass plate, an air film of gradually increasing thickness is formed . The thickness of the air film is symmetrical and increases outwards from the point of contact.
What will happen if the glass plate is silvered on its front surface?
What will happen if the glass plate is silvered on its front surface? Ans. The transmitted system of fringes will also be reflected and due to the superposition of the reflected and transmitted (which is also reflected now) systems the uniform illumination will result.
What happens to the radius of rings if we introduce a liquid drop between lens and glass plate?
Since the gap between the glasses increases radially from the center, the interference fringes form concentric rings. The thickness of the rings decreases as their diameter decreases. ... Thus, the diameter of the rings contract when a drop of water is introduced between the lens and the glass plate.
Why the Rings crowded when we go away from the center?
Rings get closer as the order increases (m increases) since the diameter does not increase in the same proportion. In transmitted light the ring system is exactly complementary to the reflected ring system so that the centre spot is bright.
Why is the central spot is dark?
Why is the central fringe is dark? The central fringe in Newton’s rings is dark in the case of the reflected system because the air film thickness formed at the centre between the glass plate and the lens is zero . ... But due to reflection, a path difference of (λ/2) is introduced.
Why is the glass plate inclined at 45 degrees?
The angle between the incoming ray and the glass plate is 45 degree to make turns the light rays to 90 degrees and that’s why the rays fall normally on the plano-convex lens. Finally forms circular rings.
Which source is used in Newton’s rings experiment?
To study the formation of Newton’s rings in the air-film in between a plano-convex lens and a glass plate using nearly monochromatic light from a sodium-source and hence to determine the radius of curvature of the plano-convex lens.
Why are Newton’s rings are not equally spaced?
Spacing between Fringes
The Newton’s rings are not equally spaced because the diameter of ring does not increase in the same proportion as the order of ring and rings get closer and closer as ‘n’ increases .
What happens if the glass plate is replaced by mirror?
If we replace the glass plate with a mirror then, we will not get any interference fringe because the intensity of light reflected from the mirror will be so great that it won’t be visible and we will get uniform illumination.
What will happen if we use white light instead of sodium light?
all fringes will appear dark . only the central fringe will be white, all other will look colourful.
What will happen if few drops of water is introduced in the space between the plano convex lens and the plane glass plate?
Therefore when a drop of water is introduced between the glass plate and plano-convex lens then the refractive index of the medium between them increases . So the ring system contracts in Newton’s ring system.
When the liquid is introduced between the lens and plate the diameter of the rings?
When a liquid is introduced into the air space between the lens and the plate in a Newtons-rings apparatus,the diameter of the tenth ring changes from 1.50 to 1.31 cm .
When a drop of water is introduced between?
The distance across of Newton’s rings is conversely relative to refractive record. So when a drop of water is presented between the glass plate and Plano-raised focal point in Newton’s rings, the ring framework contacts.
When the liquid is introduced between the lens and plate the diameter of the rings Mcq?
For minimum thickness, we take n = 1. = 214.3 nm. 15. In Newton’s ring experiment, the diameter of the 10 th ring changes from 1.40 to 1.23 cm when a liquid is introduced between the lens and glass plate.
