How r power and focal length of a lens related? U r provided with two lenses of focal length 20cm and 40cm respectively which lens will u use to obtain more convergent light?
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The power of a lens is related to its focal length as P = 1/f (in m). More the power of a lens more is its converging power. Thus, the lens of shorter focal length will have more converging power. so I will use lens with the focal length of 20 cm.