Question

Write down the characteristics of an image formed by concave
mirror when the object is placed

Answer 1

(a) Between C &F

Image is formed beyond ‘C.’

The nature of the image is enlarged, inverted & real.

(b) At F

Image is formed at infinity.

The nature of the image enlarged, inverted & real.

Answer 2

Angle A + Angle C = 180°

(x + y + 10) + (x + y - 30) = 180°

2x + 2y - 20 = 180°

2x + 2y - 20 - 180° = 0

2x + 2y - 200° = 0

(Divide the whole equation by 2)

x + y - 100 = 0 .....(1)

Now, Angle B + Angle C = 180°

(y + 20) + (x + y) = 180°

2y + 20 + x = 180°

x + 2y + 20 - 180° = 0

x + 2y - 160 = 0 ....(2)

Subtracting eqn (1) & (2)

x + y = 100

±x ± 2y = - 160

- y = -60

∴ y = 60

Putting the value in eqn (1)

x + y - 100 = 0

x + 60 - 100 = 0

x - 40 = 0

∴ x = 40

Putting the value of x and y in Given angles.

angleA = (x + y + 10) = 110°

angleB = (y + 20) = 80°

angleC = (x + y - 30) = 80

angleD = (x + y) = 100