Formative

Question 1

Chromatic aberration

Answer 1

As white light passes through a lens it is dispersed into a spectrum. This occurs because different wavelengths are refracted by different amounts, The differing amounts of refraction result in each wavelength focusing at different points in the image place, this causes burring and coloured fringes

Question 2

Toric Lens

Answer 2

2 principal meridians have different curvatures, therefore different refractive powers and subsequent focal lengths. A point will produce line foci in image plane.

Question 3

Total internal reflection

Answer 3

Light ray is within higher refractive index, it tries to pass to a lower refractive index but the angle of incidence at the boundary is greater than the critical angle. Under these circumstances refraction cannot occur, instead the ray is totally internally reflected

Question 4

Aparant size

Answer 4

Apparent size takes both object size and object distance from the eye into account. An object will have a larger apparent size if brought closer to the eye, this is because it subtends a larger angle.