Suppose that the electric field part of an electromagnetic wave in vacuum is `vec(E )={(3.1 N//C)cos [(1.8 rad//m)y+(5.4xx10^(6)rad//s)]}hat(i)`
What is the wavelength `lambda` ?

Explanation

Comparing given equation,
`vec(E )=3.1 cos {(5.4xx10^(6))t+(1.8)y}hat(i)` (With all values in SI units) with standard form `E=E_(0)cos (omega t + ky)` we get,
`E_(0)=3.1 (N)/(C ) " "` …(2)
`omega = 5.4xx10^(6)(rad)/(s) " "` ....(3)
`k=1.8(rad)/(m) " "` ....(4)
`therefore (2pi)/(lambda)=1.8 rArr lambda = (2xx3.14)/(1.8)=3.489 m`
`~~3.5 m " "` ....(5)