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. |
- A small object is placed 150 mm away from a diverging lens of focal length 100 mm.
- Copy the figure below and draw rays to show how an image is formed by the lens.
- Calculate the distance of the image from the lens by using the lens formula.
- Copy the figure below and draw rays to show how an image is formed by the lens.
- The diverging lens in part (a) is replaced by a converging lens also of focal length 100 mm. The object remains in the same position and an image is formed by the converging lens. Compare two properties of this image with those of the image formed by the diverging lens in part (a).
How is a spherical mirror used to converge a beam of light at a point? Name the type of mirror used.
A student obtained on a screen the sharp image of a candle flame placed at the farther end of laboratory table using a concave mirror. For getting better value of focal length of the mirror, the teacher suggested to him to focus the sun. What should the student do?
(A) Should move the mirror away from the screen.
(B) Should move the mirror towards the screen.
(C) Should move the mirror and screen both towards the sun.
(D) Should move only the screen towards the sun.
If a spherical mirror breaks, what type of mirrors are the individual pieces?
Draw a ray diagram to show the formation of image by a concave mirror for the object beyond its centre of curvature. State three characteristics of the image.
Upto what maximum distance from a concave mirror, the image can be obtained? What will be the location of object for it?
Find the height of the image of a body of height 1.5m in a mirror with a magnification of 1.5.
Define the term Principle focus.
