The magnetic field of a beam emerging from a filter facing a floodlight is given by `B=12xx10^-8sin(1.20xx10^7z-3.60xx10^14t)T`.
What is the average intensity of the beam?

Explanation

Magnetic field `B=B_(0) "sin"omegat`
Given equation `B=12 xx 10^(-8) " sin"(120 xx 10^(7) z-3.60 xx 10^(15) t)T.`
On comparing this equation with standard equation we get
`B_(0) =12 xx 10^(-8)`
The average intensity of the beam`I_(av) =(1)/(2)(B_(0)^(2))/(mu_(0)) .c =1/2 xx((12 xx 10^(-8))^(2)xx 3 xx 10^(8))/(4pixx 10^(-7))`
`=1.71 W//m^(2)`