Question

A spherical mirror produces an image of magnification -1 on a screen placed at a distance of 50cm from the mirror

a. write the type of mirror

b Find the distance of the image from the object

c What is the focal length of the mirror?

d. Draw the ray diagram to show the image formation in this case.​

Answer 1

A spherical mirror produces an image of magnification -1 on a screen placed at a distance of 50 cm from the mirror.

a. Write the type of mirror.

Ans. It is concave mirror because the image is formed on the screen, so it is real and inverted image which is formed by concave mirror. Also if magnification has minus sign ( - ), the image is real and inverted.

b. Find the distance of the image from the object.

Ans.

⇛If magnification, m = - 1

⇛ v = 50 cm

Now, we know that if magnification has minus sign ( - ), the image is real and inverted.

∴ v = - 50 cm ( for real image )

Then, m = -v/u

Putting the values in,

➟ - 1 = - ( - 50 )/ u

➟ u = - 50 cm

∴ The distance of the image from the object = - 50 cm

c. What is the focal length of the mirror?

By using mirror formula,

✰ 1/f = 1/v + 1/u

Putting the values in the formula,

➟ 1/f = 1/-50 + 1/-50

➟ 1/f = - 1/50 - 1/50

➟ 1/f = -1-1/50

➟ 1/f = -2/50

➟ 1/f = -1/25

➟ f = - 25 cm

∴ The focal length of the mirror = - 25 cm

d. Draw the ray diagram to show the image formation in this case.

Ans. Refer the attachment ⛈

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