The wavefront of a light beam is given by the equation `x + 2y + 3x = c` (where c is arbitrary constant), then the angle made by the direction of light with the y-axis is

Options

A. `cos^(-1).(1)/(sqrt(14))`
B. `sin^(-1).(2)/(sqrt(14))`
C. `cos^(-1).(2)/(sqrt(14))`
D. `sin^(-1).(3)/(sqrt(14))`

Answer

C

Explanation

Here direction of light is given by normal vector `vec(n)=hati+2hatj+3hatk`
`:.` angle made by the `vec(n)` with y-axis is given by `cos beta= 2/(sqrt(1^(2)+2^(2)+3^(2)))=2/(sqrt(14))`