Question

An electromagnetic wave strikes a 1.12-cm2 section of wall perpendicularly. the rms value of the wave's magnetic field is determined to be 5.50 Ã 10-4 t. how long does it take for the wave to deliver 2780 j of energy to the wall?

Answer 1

0.34 s

Step-by-step explanation:

We are given that

Area,A=
`1.12 cm^2=1.12* 10^(-4) m^2`

`1cm^2=10^(-4) m^2`

Magnetic field,B=
`5.5* 10^(-4) T`

Energy,E=2780 J

Intensity of electromagnetic wave which strikes the wall ,
`I=(B^2)/(\mu_0)c`

Where
`\mu_0=4\pi* 10^(-7)`

`c=3* 10^8 m/s`

`I=((5.5* 10^(-4))^2)/(4\pi* 10^(-7))* 3* 10^8`

`I=7.22* 10^7W/m^2`

Average power emitted by electromagnetic wave,
`P_(avg)=IA=7.22* 10^7* 1.12* 10^(-4)=8086.4 W`

Time,t=
`(E)/(P_(avg))`

`t=(2780)/(8086.4)=0.34 s`