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A red LED emits light at 0.1 watt uniformly around it. The amplitude of the electric field of the light at a distance of 1 m from the diode is
What are the essential properties a medium must possess for the propagation of mechanical waves?
The friction force amongst the particles of the medium should be negligibly small so that they continue oscillating for a sufficiently long time and the wave travels a sufficiently long distance through the medium
The relationship between α and β is given by
A radiation energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is PE/C, then P is -
Find the deviation of light ray (in degree)
In the arrangement shown a point source of light S is placed 60 cm to the left of a convex lens of focal length 30 cm and 2 cm above the common principal axis of the convex lens and a convex mirror of focal length 10 cm. Consider optic centre of the lens to be the origin, the x-coordinate of the final image of the source S for the viewer left to the lens is equal to (– K) cm. Calculate the value of K.
An isotropic point source of light is kept at distance of 60 cm from a screen, the intensity of light obtained on center is I1. Now a lens of focal length 20 cm is introduced at exactly midway between source and screen and intensity obtained is I2. Find I2/8I1.
A wave of frequency 100 Hz travels along a string towards its fixed end. When this wave travels back, after reflection, a node is formed at a distance of 10 cm from the fixed end. The speed of the wave (incident and reflected) is :