Advertisements
Advertisements
प्रश्न
A concave mirror of focal length 12 cm forms three times the magnified virtual image of an object. Find the distance of the object from the mirror.
Advertisements
उत्तर
Given Data:
- Focal length (f) = −12 cm (Concave mirror → Focal length is negative)
- Magnification (m) = +3 (Virtual, magnified image → Positive magnification)
- Object distance (u) = ?
Use Magnification Formula
`m = -v/u`
`3 = -v/u`
v = −3u
`1/f = 1/v + 1/u`
Substituting f = −12 and v = −3u:
`1/-12 = 1/(-3u) + 1/u`
`1/-12 = (1+3)/(3u)`
`1/-12 = 4/(3u)`
−12 × 4 = 3u
−48 = 3u
u = −8 cm
The negative sign indicates that the object is placed in front of the mirror at a distance of 8 cm from the pole.
APPEARS IN
संबंधित प्रश्न
Can mirrors give rise to chromatic aberration?
In image formation from spherical mirrors, only paraxial rays are considered because they
The image of an extended object, placed perpendicular to the principal axis of a mirror, will be erect if
(a) the object and the image are both real
(b) the object and the image are both virtual
(c) the object is real but the image is virtual
(d) the object is virtual but the image is real.
According to the mirror equation, ______.
The radius of curvature of the curved surface of a plano-convex lens is 20 cm. If the refractive index of the material of the lens be 1.5, it will ______.
The direction of ray of light incident on a concave mirror is shown by PQ while directions in which the ray would travel after reflection is shown by four rays marked 1, 2, 3 and 4 (figure). Which of the four rays correctly shows the direction of reflected ray?
An object is 20 cm away from a concave mirror and it is within the focal length of the mirror. If the mirror is changed to a plane mirror, the image moves 15 cm closer to the mirror.
Focal length of the concave mirror is ______.
Parallel rays striking a spherical mirror far from the optic axis are focussed at a different point than are rays near the axis thereby the focus moves toward the mirror as the parallel rays move toward the outer edge of the mirror. What value of incidence angle θ produces a 2% change in the location of the focus, compared to the location for θ very close to zero?
A particle is dropped along the axis from a height 15 cm on a concave mirror of focal length 30 cm as shown in figure. The acceleration due to gravity is 10 m/s2. Find the maximum speed of image in m/s:
If an object is placed at a distance of 10 cm in front of a concave mirror of a focal length of 20 cm, the image formed will be ______.
