Advertisements
Advertisements
प्रश्न
Define the critical angle for a given pair of media and total internal reflection. Obtain the relation between the critical angle and refractive index of the medium.
Advertisements
उत्तर
The angle of incidence corresponding to an angle of refraction of 90° is called the critical angle for the given pair of media. If the angle of incidence of light, when travelling from a denser medium to a rarer medium, is greater than the critical angle then total internal reflection takes place.
Let the angle of incidence i and C be the critical angle C.
Let the angle of refraction r = 90°.
The refractive index of the rarer medium is μa.
The refractive index of the denser medium is μb.
Applying Snell's law,
`(sini)/(sinr) = mu_a/mu_b`
μb sinC = μa sin90° ....[∵ i = C and r = 90°]
`mu_a/mu_b = 1/(sinC)`
Thus, we arrive at a formula expressing the critical angle and refractive index relation:
`""_amu_b = 1/(sinC)`
APPEARS IN
संबंधित प्रश्न
A point source of light is placed at a distance of 2 f from a converging lens of focal length f. The intensity on the other side of the lens is maximum at a distance
An extended object is placed at a distance of 5.0 cm from a convex lens of focal length 8.0 cm. (a) Draw the ray diagram (to the scale) to locate the image and from this, measure the distance of the image from the lens. (b) Find the position of the image from the lens formula and see how close the drawing is to the correct result.
Two convex lenses, each of focal length 10 cm, are placed at a separation of 15 cm with their principal axes coinciding. (a) Show that a light beam coming parallel to the principal axis diverges as it comes out of the lens system. (b) Find the location of the virtual image formed by the lens system of an object placed far away. (c) Find the focal length of the equivalent lens. (Note that the sign of the focal length is positive although the lens system actually diverges a parallel beam incident on it.)
Use the above relation to obtain the condition on the position of the object and the radius of curvature in terms of n1and n2 when the real image is formed.
Obtain an expression for refraction at a single convex spherical surface, i.e., the relation between μ1 (rarer medium), μ2 (denser medium), object distance u, image distance v and the radius of curvature R.
Which of the following correctly states the relation for refraction at a spherical surface?
According to the Cartesian sign convention for refraction at a spherical surface, all distances are measured from:
In the derivation of the spherical surface refraction formula, which approximation is applied to the angles made by the incident ray, refracted ray, and normal?
Which set of variables is primarily involved in refraction at a spherical surface, as opposed to refraction at a plane surface?
An object is placed at a distance of 100 cm in air from a convex spherical surface of glass of refractive index 1.5. The radius of curvature is 20 cm. What is the image distance?
