Physics, asked by Lakeesha, 1 month ago

A concave mirror of focal length 10 cm is placed in front of an object find the positions of the object for which image size is thrice that of size of the object?​

Answers

Answered by rsagnik437
53

Answer :-

Position of the object is 6.67 cm from the mirror.

Explanation :-

We have :-

• Focal length of the mirror = 10 cm

• Size of the image is thrice the size of the object.

________________________________

According to the question :-

→ hᵢ = 3hₒ

We know that :-

m = -(v/u) = h/h

⇒ -(v/u) = 3hₒ/hₒ

⇒ -(v/u) = 3

⇒ v/u = -3

⇒ v = -3u

________________________________

Since the mirror is concave, we have :-

→ f = -10 cm

According to mirror formula :-

1/v + 1/u = 1/f

⇒ 1/(-3u) + 1/u = 1/(-10)

⇒ -1/3u + 1/u = -1/10

⇒ [-1 + 3]/3u = -1/10

⇒ 2/3u = -1/10

⇒ 3u(-1) = 2(10)

⇒ -3u = 20

⇒ u = 20/-3

u = - 6.67 cm

Answered by Anonymous
23

Answer:

Given :-

A concave mirror of focal length 10 cm is placed in front of an object

To Find :-

Position

Solution :-

Since the size of of image is trice So,

hi = 3 × ho = 3ho

Magnification = -v/u = hi/ho

-v/u = hi/ho

Putting hi as 3ho

-v/u = 3ho/ho

v/u = -3ho/ho

Cancellation of ho

v/u = -3

By cross multiplication

v = -3 × u

v = -3u

By using mirror formula

1/f = 1/u + 1/v

1/-10 = 1/u + 1/-3u

-1/10 = 1/u + -1/3u

-1/10 = 3 + (-1)/3u

-1/10 = 3 - 1/3u

-1/10 = 2/3u

By cross multiplication

-1(3u) = 10(2)

-3u = 20

-u = 20/3

u = -20/3

u = -6.67 cm

 \\

Similar questions