Question

The electric field in a plane electromagnetic wave is given by `vecE = 200cos[((0.5 xx 10^3)/m)x - (1.5 xx 10^11 "rad"/s xx t)]V/mhatj`. If the wave falls normally on a perfectly reflecting surface having an area of 100 cm². If the radiation pressure exerted by the E.M. wave on the surface during a 10-minute exposure is `x/10^9 N/m^2`. Find the value of x.

पर्याय

• 350

• 351

• 354

• 355

Answer 1

354

Explanation:

We can find the required parameter and then use the formula by comparing the given equation with E = E₀ cos(kx - wt).

Radiation pressure = `21/c`

and `I = 1/2ε_0E_0^2c`

Radiation Pressure = `21/c = (2/c)(1/2ε_0E_0^2c) = ε_0E^2`

Here, E = 200 `V/m` and `ε_0 = 8.85 xx 10^-12`

Radiation Pressure = `8.85 xx 10^-12 xx (200)^2`

= `354.0 xx 10^-9 "N""/""m"^2`