Advertisements
Advertisements
Question
At what distance from a concave mirror focal length 10 cm should an object 2 cm long be placed in order to get an erect image 6 cm tall?
Solution
Height of the object 'ho' = 2 cm
Focal length of the mirror 'f' = −10 cm
Height of the image 'hi' = 6 cm
We have to find the distance of the object from the mirror 'u'.
Using the magnification formula, we get
`m= h_i/h_o=-v/u`
`m=6/2=-v/u`
`m=3=-v/u`
thus v=-3u
Now, using the mirror formula, we get
`1/f=1/v+1/u`
`1/-10=1/(-3u)+1/u`
`1/10=1/(3u)-3/(3u) =(-2)/(3u)`
`u=(-2xx10)/3`
u=-6.67 cm
Thus, the distance of the object from the mirror 'u' is −6.67 cm.
APPEARS IN
RELATED QUESTIONS
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.
A ray of light is incident on a plane mirror making an angle of 90° with the mirror surface. The angle of reflection for this ray of light will be:
(a) 45°
(b) 90°
(c) 0°
(d) 60°
ill in the following blank with suitable word:
For a convex mirror, parallel rays of light appear to diverge from a point called the ......... .
What is the position of the image when an object is placed at a distance of 20 cm from a concave mirror of focal length 20 cm?
A concave mirror produces three times enlarged virtual image of an object placed at 10 cm in front of it. Calculate the radius of curvature of the mirror.
If the object is moved further away from the mirror, what changes are there in the position and size of the image?
What would your image look like if you stood close to a large:
concave mirror?
The mirror used by a dentist to examine the teeth of a person is:
(d) any one of the above
(a) convex
(b) concave
(c) plane
(d) any one of the above
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.
Give any two applications of a concave and convex mirror.
