Question

Q 18:
18. The wavefront of a light beam is given by the equation x+2y+3z=c, (where c is a constant) then the angle made by the direction of light with the y-axis is.
(1) cos-11√14 (2) cos-12√14(3) sin -11√14 (4) sin -12√14

Answer 1

Answer:

the wavefront equations must be of form ax+by+cz=1 where a

2

+b

2

+c

2

=1 (a,b,c are cosines of angles made with x,y,z axes respectively)

applying this to the given equation ,

1

2

+2

2

+3

2

=c

2

c

2

=14

c=

14

angle made with y-axis is cos

−1

14

2