Ray Optics and Optical Instruments – Solutions

1) A small candle, 2.5 cm in size, is placed 27 cm in front of a concave mirror of radius of curvature 36 cm. at what distance from the mirror should a screen be placed to obtain a sharp image? Describe the nature and size of the image. If the candle is moved closer to the mirror, where would be the screen have to be moved?

Solution:

Focal length, f = R/2 = -18 cm

Distance given that

Size of object, O = 2.5 cm

Distance of object, u = -27 cm

Of image = v=?

Size of image, I =?

Using mirror formula,