Advertisements
Advertisements
प्रश्न
An object of length 4 cm is placed in front of a concave mirror at distance 30 cm. The focal length of mirror is 15 cm.
- Where will the image form?
- What will be the length of image?
Advertisements
उत्तर
O = 4 cm
u = -30 cm
f = -15 cm
From mirror formula ,
`1/"f" = 1/"v" + 1/"u"`
∴ `1/"v" = 1/"f" - 1/"u"`
∴ `1/"v" = 1/(-15) - 1/(-30) = 1/30 - 1/15`
∴ `1/"v" = (-1)/30`
∴ v = -30 cm
Hence , the image is formed at a distance of 30 cm in front of the mirror .
m = `-"v"/"u" = "I"/"O"`
∴ I = `"-OV"/"u" = (-4 xx -30)/(-30) = -4`cm
Negative sign indicates inverted image.
So, I = 4 cm
Hence , the length of the image is 4 cm.
APPEARS IN
संबंधित प्रश्न
Match the items given in Column I with one or more items of Column II.
| Column I | Column II | ||
| (a) | A plane mirror | (i) | Used as a magnifying glass. |
| (b) | A convex mirror | (ii) | Can form image of objects spread over a large area. |
| (c) | A convex lens | (iii) | Used by dentists to see enlarged image of teeth. |
| (d) | A concave mirror | (iv) | The image is always inverted and magnified. |
| (e) | A concave lens | (v) | The image is erect and of the same size as the object. |
| (vi) | The image is erect and smaller in size than the object. |
Name the spherical mirror which has:
(a) virtual principal focus.
(b) real principal focus.
When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.
What is the advantage of using a carbon paper rather than a white paper?
A diverging lens is used in:
(a) a magnifying glass
(b) a car to see objects on rear side
(c) spectacles for the correction of short sight
(d) a simple camera
State the two kinds of spherical mirror and distinguish them with the aid of proper diagrams.
Explain the meaning of the terms focus and focal length in case of a convex mirror, with the help of suitable ray diagram.
Name the mirrors shown in Figure (a) and (b).
Define the following term in relation to concave mirror.
Center of curvature
Find the height of the image of a body of height 1.5m in a mirror with a magnification of 1.5.
