Physics

CAREER POINT NUMERICALS An object of size 25 cm is placed in front of a concave mirror of focal length 15 cm At what distance from the mirror should a screen be placed in order to get a sharp image. Find the nature and size also A needle 10cm long is placed along the axis of a convex lens of focal length 10 cm such that its middle point is at a distance of 20 cm from the lens Find the length of the imaged needle . Find the focal length and nature of the lens which should be placed in contact with a lens of focal length 10 cm so that the power of the combination becomes 5 D 4 Explain why white light is not dispersed while passing through a hollow glass prism 5 Explain why does the stream of hot rising above the fire appear wavering ? Surface of the goggles are curved but still they have zero power . Why ?