An object 5.0 cm in length is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm .find the position of image ,its nature and size
Dear Student
Given, Distance of the object from the convex mirror (u) = -20 cm
Radius of Curvature : 30 cm
Focal length ( f) = (30 / 2) cm
= 15 cm
Now, as we know,
1/u + 1/v = 1/f [ where f = focal length , v = distance of the image from the mirror and u = distance of the object from the mirror]
1/(-20) + 1/v = 1/15
1/v = 1/15 - (-1/20)
1/v = 1/15 + 1/20
1/v = (4 + 3) / 60
1/v = 7/60
v = 60/7
v = 8.57 cm
Therefore, distance of the image from the mirror is 8.57cm.
Now, Height of the object ( Ho) = 5 cm
Distance of the image from the mirror ( v) = 8.5cm
Distance of the object from the mirror ( u) = -20 cm
Since,Magnification (m) = Hi/Ho [ where Ho = height of the object and Hi = height of the image]
M = -v/u = - 8.5 cm / -20 cm = +0.42
Therefore Magnification (m) = -v/u= - 8.5 cm / -20 cm = +0.42
Thus, Nature = Virtual and erect
Size = Smaller in size or diminished by the factor of 0.42
Position = 8.5 cm at the back of the mirror.
Regards
Given, Distance of the object from the convex mirror (u) = -20 cm
Radius of Curvature : 30 cm
Focal length ( f) = (30 / 2) cm
= 15 cm
Now, as we know,
1/u + 1/v = 1/f [ where f = focal length , v = distance of the image from the mirror and u = distance of the object from the mirror]
1/(-20) + 1/v = 1/15
1/v = 1/15 - (-1/20)
1/v = 1/15 + 1/20
1/v = (4 + 3) / 60
1/v = 7/60
v = 60/7
v = 8.57 cm
Therefore, distance of the image from the mirror is 8.57cm.
Now, Height of the object ( Ho) = 5 cm
Distance of the image from the mirror ( v) = 8.5cm
Distance of the object from the mirror ( u) = -20 cm
Since,Magnification (m) = Hi/Ho [ where Ho = height of the object and Hi = height of the image]
M = -v/u = - 8.5 cm / -20 cm = +0.42
Therefore Magnification (m) = -v/u= - 8.5 cm / -20 cm = +0.42
The positive value of image height indicates that the image formed is erect.
Therefore, the i mage formed is virtual, erect, and smaller in size.
Thus, Nature = Virtual and erect
Size = Smaller in size or diminished by the factor of 0.42
Position = 8.5 cm at the back of the mirror.
Regards