a 2 cm object is placed at a distace of 20 cm from a concave mirror a real image is formed 40 cm from the mirror. calculate the focal length of the mirror and size of the image
Answers
Answer:
Explanation:
Solution,
Here, we have
Height of object = 2cm
Object distance, u = - 20 cm
Image distance, v = - 40 cm
To Find,
Focal length, f = ?
Height of image = ?
According to the mirror formula,
We know that,
1/f = 1/v + 1/u
So, putting all the values, we get
⇒ 1/f = 1/v + 1/u
⇒ 1/f = 1/- 40 + 1/- 20
⇒ 1/f = 1/- 40 - 1/20
⇒ 1/f = - 1 - 2/40
⇒ 1/f = - 3/40
⇒ f = - 40/3
⇒ f = - 13.33 cm
Hence, the focal length is - 13.33 cm.
Now, the Height of the image,
According to the magnification formula,
We know that,
Magnification, m = h(i)/h(o) = - v/u
So, putting all the values, we get
⇒ h(i)/h(o) = - v/u
⇒ h(i)/2 = -(- 40/- 20)
⇒ h(i) = - 4 cm
Hence, the height of image is - 4 cm.
Given:
a 2 cm object is placed at a distace of 20 cm from a concave mirror a real image is formed 40 cm from the mirror.
To find:
calculate the focal length of the mirror and size of the image
STEP BY STEP EXPLANATION:
Object distance (u) = -20cm
Image distance (v) = -40cm
Height of object () = 2cm
Mirror formula
Magnification, m =
∴ the size of the image is
Hence verified !