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Refractive index of diamond with respect to glass is 1.6 and the absolute refractive index of glass is 1.5. Find out the absolute refractive index of diamond.
A 10 mm long awl pin is placed vertically in front of a concave mirror. A 10 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is
– 15 cm
– 30 cm
– 45 cm
– 60 cm
Rays from Sun converge at a point 25 cm in front of a concave mirror. Where should an object be placed so that size of its image is equal to the size of the object?
25 cm in front of the mirror
50 cm in front of the mirror
between 25 cm and 50 cm in front of the mirror
more than 50 cm in front of the mirror
Magnification produced by a rear view mirror fitted in vehicles
is less than one
is more than one
is equal to one
can be more than or less than one depending upon the position of the object in front of it.
The mirror having reflecting surface curved inwards
The image which is formed behind the mirror
If an object is placed 21 cm from a converging lens, the image formed is slightly smaller than the object. If the object is placed at a distance of 19 cm from the lens, the image formed is slightly larger than the object. The approximate focal length of the lens is:
A lens of focal length 12 cm forms an erect image, three times the size of the object. The distance between the object and image is:
Magnifying power of a concave lens is
always < 1
always > 1
always = 1
none of these
Out of seven colours of white light, which colour has maximum wavelength?
D and E are respectively the midpoints on the sides AB and AC of a triangle ABC and BC = 6 cm. If DE || BC, then the length of DE (in cm) is
Diagonals of a trapezium PQRS intersect each other at the point O, PQ || RS and PQ = 3 RS, Then the ratio of areas of triangles POQ and ROS is:
Areas of two similar triangles are 36 cm2 and 48 cm2. If the length of a side of the larger triangle is 16 cm, then the length of the corresponding side of the smaller triangle is:
In the figure given below DE || BC. If AD = x, DB = x – 2, AE = x + 2 and EC = x – 1, the value of x is:
Corresponding sides of two similar triangles are in the ratio of 2 : 3. If the area of the smaller triangle is 48 cm2, then the area of the larger triangle is: