Question
An object of size 3.0 cm is placed 14 cm in front of a concave lens of focal length 21 cm. Describe the image produced by the lens. What happens if the object is moved further away from the lens?
Solution
Size of object, O = 3.0 cm
Object distance, u = – 14 cm
Focal length, f = – 21 cm
Image distance, v = ?
Using the lens formula,
The image is located 8.4 cm from the lens on the same side as that of the object.
Magnification,
Image size,
As size of image is +ve. So, image is errect and virtual of smallar size.
As the object is moved away from the lens, the virtual image moves towards the focus of the lens but never beyond. The image progressively diminishes in size.
Object distance, u = – 14 cm
Focal length, f = – 21 cm
Image distance, v = ?
Using the lens formula,
The image is located 8.4 cm from the lens on the same side as that of the object.
Magnification,
Image size,
As size of image is +ve. So, image is errect and virtual of smallar size.
As the object is moved away from the lens, the virtual image moves towards the focus of the lens but never beyond. The image progressively diminishes in size.
