AP EAMCET2008PhysicsRay Optics
An achromatic combination of lenses produces
Options
- Aimages in black and white
- Bcoloured images
- Cimages unaffected by variation of refractive index with wavelength
- Dhighly enlarged images are formed
Correct answer
C. images unaffected by variation of refractive index with wavelength
Step-by-step solution
The image of an object in white light formed by a lens is usually coloured and blurred. This defect of image is called chromatic aberration and arises due to the fact that focal length of a lens is different for different colours. In case of two thin lenses in contact, the combination will be free from chromatic aberration. The lens combination which satisfies this condition are called achromatic lenses.