Q16 of 31 Page 185

Find the focal length of a lens of power, -2.0 D. What type of lens is this?

The power of this lens has a negative sign (or minus sign), so this is a concave lens. Now,

Power, P =


So, -2.0 =


And, m


Or, cm


So, Focal length of lens, f = -50 cm


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