Monochromatic light of frequency 5 x 10⁴ Hz travelling in vacuum enters a medium of refractive index 1.5. Its wavelength in the medium is :
At what distance from a screen will a 27 Cd lamp provide the same illumination as a 75 Cd lamp 15 m from the screen?
In an astronomical telescope the focal length of objective lens is 100 cm and that of eyepiece is 2 cm. The magnifying power of the telescope for the normal eye is
Large aperture objects are used in telescopes because they
Large aperture objects are used in telescopes because they Read More »
Light with wavelength of 6000 A0 units has a frequency
Light with wavelength of 6000 A0 units has a frequency Read More »
A ray reflected successively from two plane mirrors inclined at a certain angle undergoes a deviation of 3000. Then the number of images observable is :
In order to obtain a magnification of, -0.6 (minus 0.6) with a concave mirror, the object must be placed
An object is placed 20 cm in front of a plane mirror. The mirror is moved 2 cm towards the object. The distance between the positions of the original and final images seen in the mirror is
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:
Which position of the object will produce a magnified virtual image, if a concave mirror of focal length 15 cm is being used?
