A luminous point is moving at speed v0 towards a spherical mirror, along its axis. Then the speed at which the image of this point object is moving is given by (with R = radius of curvature and u = object distance):  


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A ray of light falls on a transparent glass slab with refractive index (relative to air) of 1.62. The angle of incidence for which the reflected and refracted rays are mutually perpendicular is: 


A concave mirror of focal length f produces an image n times the size of the object. If the image is real, then the distance of the object from the mirror is:    


A convex mirror of focal length f produces an image (1/n)th of the size of the object. The distance of the object from the mirror is: 


A short linear object of length L lies on the axis of a spherical mirror of focal length f at a distance u from the mirror. Its image has an axial lengthL’ equal to: 


A thin convergent glass lens (μg = 1.5) has a power of +5.0 D. When this lens is immersed in a liquid of refractive index  it acts as a divergent lens of focal length 100 cm. The value of μl must be:


The sun (diameter = D) subtends an angle of θ radians at the pole of a concave mirror of focal length f. The diameter of the image of the sun formed by the mirror is: 


A double convex lens of focal length 6 cm is made of glass of refractive index 1.5. The radius of curvature of one surface is double that of the other surface. The value of smaller radius of curvature is:


Diameter of a plano-convex lens is 6 cm and thickness at the centre is 3 mm. If the speed of light in the material of the lens is , the focal length of the lens is:  


A slide projector gives a magnification of 10. If it projects a slide of dimensions 3 cm × 2 cm on a screen, the area of the image on the screen will be: 


An equiconvex glass lens (a) has a focal length f and power P. It is cut into two symmetrical halves (b) by a plane containing the principal axis. The two pieces are recombined as shown in fig. (c) The power of new combination is: