Advertisements
Advertisements
प्रश्न
You are given four sources of light each one providing a light of a single colour – red, blue, green and yellow. Suppose the angle of refraction for a beam of yellow light corresponding to a particular angle of incidence at the interface of two media is 90°. Which of the following statements is correct if the source of yellow light is replaced with that of other lights without changing the angle of incidence?
पर्याय
The beam of red light would undergo total internal reflection.
The beam of red light would bend towards normal while it gets refracted through the second medium.
The beam of blue light would undergo total internal reflection.
The beam of green light would bend away from the normal as it gets refracted through the second medium.
Advertisements
उत्तर
The beam of blue light would undergo total internal reflection.
Explanation:
According to the Cauchy relationship, `lambda oo 1/mu`
Smaller the wavelength higher the refractive index and consequently smaller the critical angle.
We know `v = flambda`, the frequency of wave remains unchanged with medium hence `v oo lambda`.
The critical angle, sin C = `1/mu`
Also, velocity of light, `v oo 1/mu`
According to VIBGYOR, among all given sources of light, the blue light have smallest wavelength, As `lambda_("blu") < lambda_("yellow")` hence `v_("blue") < v_("yellow")`, it means `mu_("blue") > mu_("yellow")`
It means critical angle for blue is less than yellow colour, the critical angle is least which facilitates total internal reflection for the beam of blue light.
APPEARS IN
संबंधित प्रश्न
A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of the image and the magnification. Describe what happens as the needle is moved farther from the mirror.
A spherical surface of radius 30 cm separates two transparent media A and B with refractive indices 1.33 and 1.48 respectively. The medium A is on the convex side of the surface. Where should a point object be placed in medium A so that the paraxial rays become parallel after refraction at the surface?
A narrow pencil of parallel light is incident normally on a solid transparent sphere of radius r. What should be the refractive index is the pencil is to be focussed (a) at the surface of the sphere, (b) at the centre of the sphere.
A converging lens and a diverging mirror are placed at a separation of 15 cm. The focal length of the lens is 25 cm and that of the mirror is 40 cm. Where should a point source be placed between the lens and the mirror so that the light, after getting reflected by the mirror and then getting transmitted by the lens, comes out parallel to the principal axis?
Consider the situation shown in figure. The elevator is going up with an acceleration of 2.00 m s−2 and the focal length of the mirror is 12.0 cm. All the surfaces are smooth and the pulley is light. The mass-pulley system is released from rest (with respect to the elevator) at t = 0 when the distance of B from the mirror is 42.0 cm. Find the distance between the image of the block B and the mirror at t = 0.200 s. Take g = 10 m s−2.
Focal length of a mirror is given by ______.
The radius of curvature of the curved surface of a plano-convex lens is 20 cm. If the refractive index of the material of the lens be 1.5, it will ______.
The direction of ray of light incident on a concave mirror is shown by PQ while directions in which the ray would travel after reflection is shown by four rays marked 1, 2, 3 and 4 (figure). Which of the four rays correctly shows the direction of reflected ray?
A car is moving with at a constant speed of 60 km h–1 on a straight road. Looking at the rear view mirror, the driver finds that the car following him is at a distance of 100 m and is approaching with a speed of 5 km h–1. In order to keep track of the car in the rear, the driver begins to glance alternatively at the rear and side mirror of his car after every 2 s till the other car overtakes. If the two cars were maintaining their speeds, which of the following statement (s) is/are correct?
An object is 20 cm away from a concave mirror and it is within the focal length of the mirror. If the mirror is changed to a plane mirror, the image moves 15 cm closer to the mirror.
Focal length of the concave mirror is ______.
Parallel rays striking a spherical mirror far from the optic axis are focussed at a different point than are rays near the axis thereby the focus moves toward the mirror as the parallel rays move toward the outer edge of the mirror. What value of incidence angle θ produces a 2% change in the location of the focus, compared to the location for θ very close to zero?
A converging lens has a focal length of 10 cm in air. It is made of a material with a refractive index of 1.6. If it is immersed in a liquid of refractive index 1.3, find its new focal length.
Why does a car driver use a convex mirror as a rear-view mirror?
The geometric centre of a spherical mirror is called its:
The line joining the pole and the centre of curvature of a spherical mirror is called the:
The angle of incidence is the angle between:
According to the laws of reflection, the incident ray, the reflected ray, and the normal to the reflecting surface at the point of incidence:
The laws of reflection are valid:
For a curved surface such as a spherical mirror, the normal used in applying the laws of reflection is taken as:
