Paragraph for Question Nos. 17 to 19
The figure shows a surface XY separating two transparent media, medium-1 and medium-2. The lines ab and cd represent wavefronts of a light wave travelling in medium-1 and incident on XY. The lines ef and gh represent wavefronts of the light wave in medium-2 after refraction.
(Figure: parallel straight wavefronts ab and cd in medium-1 above the boundary XY, and parallel straight wavefronts ef and gh in medium-2 below it, closer together and inclined differently.)
(The paragraph is not printed in the official archive copy (which reproduces only the questions with their answers); its text is restored from the JEE 2007 question paper.)