(a) List four characteristics of the image formed by plane mirror.(b) Concave mirror produces 4 times magnified real image of an object. If the focal length is 40 cm, then find image and the object distance?(c) An object is placed at a distance of 15 cm from a concave mirror of focal length 6cm. If the height of the object is 4cm, find the distance, nature and size of image.
Answers
Answer:
List four characteristics of the image formed by plane mirror. (b) Concave mirror produces 4 times magnified real image of an object. If ...
Mirror images
Explanation:
(a) Light rays that fall on the planar surface of the mirror, have the same angle of reflection and angle of incidence. The image is virtual, upright and of the same size as the object. The distance of the image is the same as the distance of the object from a plane mirror.
(b) Given f = 40 cm, and magnification is 4x.
1 / f = 1 / u + 1 / v
magnification (m) = - 4 (Negative sign for real image, which is inverted) = - v / u, so v = 4u
1/40 = 1/u + 1/4u = 5/4u
u = 5 * 40 / 4 = 50 cm
v = 4*-50 = -100 cm (negative sign indicates that the image is also formed to the left side of the mirror. )
(c) u = 15 cm from a concave mirror. focal length f = 6cm.
height of the object = 4cm
find the distance, nature and size of image.
1 / f = 1 / u + 1 / v
1/ 6 = 1/15 + 1/v
1/ 6 - 1/ 15 = 1/v
5 - 2 / 30 = 1/v
1/10 = 1/v
v = -10 cm
therefore, it is real and inverted.
Magnification = -v / u = -10 / 15 = -2/3 (less than 1)
Since, magnification in lesser than 1, Image is smaller than object.
Characteristics of the image are real, inverted and reduced.