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(d) a concave lens
(a) 90 cm
(a) +10cm
(c) 0 degree
(a) d<20cm
(b) less than one
(b) very near to the focus of the reflector
(a) 10cm from the mirror
(a) 30cm in front of mirror
(b) negative
The image of an object formed by an optical device is always virtual and small. The device may be
(d) a concave lens
(d) a concave lens
See lessThe focal length of a concave mirror lens is 18cm and the size of the image is a quarter of the object. The object is situated at a distance of
(a) 90 cm
(a) 90 cm
See lessTwo lenses of power +12D and -2D are placed in contact. The focal length of the combination is
(a) +10cm
(a) +10cm
See lessA ray of light continues to move along the same path while passing through an air-glass interface. The angle of incidence for the light ray is
(c) 0 degree
(c) 0 degree
See lessTo form an erect image twice the size of an object by using a convex lens of focal length 20cm the object should be placed at a distance ‘d’ from the optical centre of lens.Here’d’ is
(a) d<20cm
(a) d<20cm
See lessA light ray enters from medium A to medium B. The refractive index of medium Be to medium A will be relativ
(b) less than one
(b) less than one
See lessIn tourches search lights and head lights of vehicle the bulb is placed
(b) very near to the focus of the reflector
(b) very near to the focus of the reflector
See lessA virtual, erect and magnified image of an object is to be produced with a concave mirror of focal length 12cm. Object may be placed at a distance of
(a) 10cm from the mirror
(a) 10cm from the mirror
See lessRays from sun converge at a point 15cm in front of a concave mirror. Where should an object be placed so that size of the image is exactly equal to the size of the object?
(a) 30cm in front of mirror
(a) 30cm in front of mirror
See lessIn case of a real an inverted image the magnification of a mirror is
(b) negative
(b) negative
See less