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प्रश्न
Define the term 'focal length of a mirror'.
उत्तर
The distance between the centre of a lens or curved mirror and its focus.
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संबंधित प्रश्न
What type of wavefront will emerge from a (i) point source, and (ii) distance light source?
The equation of refraction at a spherical surface is \[\frac{\mu_2}{\nu} - \frac{\mu_1}{\mu} = \frac{\mu_2 - \mu_1}{R}\]
Taking \[R = \infty\] show that this equation leads to the equation
\[\frac{\text{ Real depth }}{\text{ Apparent depth }} = \frac{\mu_2}{\mu_1}\]
for refraction at a plane surface.
A slide projector has to project a 35 mm slide (35 mm × 23 mm) on a 2 m × 2 m screen at a distance of 10 m from the lens. What should be the focal length of the lens in the projector?
A particle executes a simple harmonic motion of amplitude 1.0 cm along the principal axis of a convex lens of focal length 12 cm. The mean position of oscillation is at 20 cm from the lens. Find the amplitude of oscillation of the image of the particle.
A converging lens of focal length 15 cm and a converging mirror of focal length 10 cm are placed 50 cm apart. If a pin of length 2.0 cm is placed 30 cm from the lens farther away from the mirror, where will the final image form and what will be the size of the final image?
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.
A spherical surface of radius R separates two medium of refractive indices µ1 and µ2, as shown in figure. Where should an object be placed in the medium 1 so that a real image is formed in medium 2 at the same distance?
A point object in the air is placed symmetrically at a distance of 60 cm in front of a concave spherical surface with a refractive index of 1.5. If the radius of curvature of the surface is 20 cm, find the position of the image formed.
Assertion: If critical angle of glass-air pair `("μg" = 3/2)` is θ1 and that of water-air pair `("μw" = 4/3)` is θ2, then the critical angle for the water-glass pair will lie between θ1 and θ2.
Reason: A medium is optically denser if its refractive index is greater.
