

Explanation
(a) A Wavefront is a surface over which particles vibrate in the same phase.

(b)(i) Glass prisms are used practically for
(I) changing direction of light I dispersion
(II) viewing distant objects (Binoculars)
(III) determing refractive index of glass
(IV) viewing objects over obstacles (periscope)

(ii) The factors include:
(I) Angle of incidence
(II) refractive index of the prism
(III) refracting angle of the prism

(iii)



(c)





(ii) (\(alpha\)) Magnifiation = \(\frac{F_o}{F_e}\); 5 = \(\frac{100}{Fe}\)
fe = 20cm
(\(\beta\)) length of telescope = \(F_o + F_e = 100 + 20\)
= 120cm

