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प्रश्न
How far should an object be placed from the pole of a converging mirror of focal length 20cm to form a real image of the size exactly `1/4`th the size of the object?
उत्तर
Given,
Focal length of the concave mirror (f) = 20 cm
Magnification (m) = -1/4
Using the magnification formula, we get
`m=-v/u`
`-1/4=(-v)/u`
`v=u/4`
Using the mirror formula, we get
`1/f=1/v+1/u`
`1/-20=4/u+1/u`
`-1/20=5/u`
u=−100 cmThus, the object should be placed in front of the concave mirror at a distance of 100 cm.
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संबंधित प्रश्न
Draw a ray diagram to show the path of the refracted ray in each of the following cases:-
A ray of light incident on a concave lens is
(i) passing through its optical centre.
(ii) parallel to its principal axis.
(iii) directed towards its principal focus.
A student wants to project the image of a candle flame on a screen 48 cm in front of a mirror by keeping the flame at a distance of 12 cm from its pole.
(a) Suggest the type of mirror he should use.
(b) Find the linear magnification of the image produced.
(c) How far is the image from its object?
(d) Draw ray diagram to show the image formation in this case.
A spherical mirror produces an image of magnification −1 on a screen placed at a distance of 40 cm from the mirror:
(i) Write the type of mirror.
(ii) What is the nature of the image formed?
(iii) How far is the object located from the mirror?
(iv) Draw the ray diagram to show the image formation in this case.
Radius of curvature of a spherical mirror is ............. its focal length.
If the radius of curvature of a concave mirror is 20 cm, its focal length is:
A student has focused the image of a candle flame on a white screen using a concave mirror. The situation is as given below:
Length of the flame = 1.5 cm
Distance of flame from the mirror = 18 cm
If the flame is perpendicular to the principal axis of the mirror, then calculate the following:
- Distance of the image from the mirror
- Length of the image
If the distance between the mirror and the flame is reduced to 10 cm, then what would be observed on the screen? Draw ray diagram to justify your answer for this situation.
Study the following ray diagram and list two mistakes committed by the student while tracing it. Rectify these mistakes by drawing the correct ray diagram to show the real position and size of the image corresponding to the position of the object AB.
According to cartesion sign convention, which mirror and which lens has negative focal length?
Rays from Sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed so that size of its image is equal to the size of the object?
Define principal focus of the concave mirror.
