1.

Let E_(0) and B_(0) denote the amplitude of electric and magnetic filed of a plane electromagnetic wave in air. The magnitude of the average momentum transferred per unit area and per unit time to a totally abosorbing surface is

Answer»

`1/2 epsi _(0) E_(0) ^(2)`
`1/2 mu_(0) B_(0)`
`epsi _(0) E_(0) ^(2)`
`(B_(0) ^(2))/(mu_(0))`

Solution :Intensity of electromagnetic wave,
`I = 1/2 epsi _(0) E_(0) ^(2)c =(1 B_(0) ^(2) c)/(mu_(0))`
where `E_(0)=` electric field and c = speed of LIGHT. Now, momentum transfer per unit area per unit time, which is also called radiation PRESSURE.
`I/A ((Deltap )/(DELTA t)) = I /c = ((1)/(2)epsi _(0) E_(0)^(2)c)/(c )`
`I /c =1/2 epsi _(0) E_(0)^(2)`
[where, `Deltap,=` momentum transferred, `DELTAT=` time and A = area.]


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