An object is placed 18cm is front of a spherical mirror .If the image is formed at.4cm to the right of the mirror , calculate its focal length . Is the mirror concave or convex . What is the nature of the image ? What is the radius of curvature of the mirror ?
Answers
Answer:
An object is placed 18cm is front of a spherical mirror .If the image is formed at.4cm to the right of the mirror , calculate its focal length . Is the mirror concave or convex . What is the nature of the image ? What is the radius of curvature of the mirror ?
Explanation:
AND UA ANSWER IS......
u = - 18 cm
v = 4 cm
1 / f = 1 / v + 1 / u
1 / f = 1 / 4 + 1 / (- 18)
1 / f = 1 / 4 - 1 / 1 8
1 / f = 9 - 2 / 36 = 7 / 36
f = 36 / 7 cm
focal length is positive so mirror is convex.
R = 2 × 36 / 7
= 72 / 7 cm
OR.....IF U DIDN'T UNDERSTAND THIS....U CAN ALSO DO LIKE THIS....
1/f=1/u+1/v
1/f=1/(-18)+1/(+4)
1/f=-2+9/36
f=36/7
R=2f
m=-v/u
f=+ve so mirror is convex
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