Question

Two plane mirrors are inclined at an angle of 720 . The number of images of a point object placed between them will be(a) 2(b) 3(c) 4(d) 5

Answer 1

answer : option (d) 5

explanation : it is given that, Two plane mirrors are inclined at an angle of 72° .

we know, The number of image of a point object placed between them,
case 1 : m = 360/angle between mirrors [ even number ]
then, the number of image = m - 1

case 2 : m = 360/angle between mirrors [ odd number ]
then, the number of image = m

here m = 360/72 = 5 [ an odd number ]

so, the number of image = 5