Answer :
An electromagnetic wave of intensity 210 w/m2 is incident normally on a rectangular black card with sides of 15 cm and 30 cm that absorbs all the radiation. 3.04 x 10^(-4) N/m^2 is the force exerted on the card by the radiation.
The force exerted on an object by electromagnetic radiation is given by the formula:
F = EI / c
where F is the force, E is the electric field strength of the radiation, I is the intensity of the radiation, and c is the speed of light in a vacuum (2.998 x 10^8 m/s).
In this case, the intensity of the radiation is 210 W/m^2 and the electric field strength is given by E = csqrt(μ/ε), where μ and ε are the magnetic permeability and electric permittivity of the medium, respectively. In a vacuum, the magnetic permeability and electric permittivity are both equal to 1, so the electric field strength of the radiation in a vacuum is
= E = csqrt(1/1) = c.
Therefore, the force exerted on the card by the radiation is:
= F = (c x 210 W/m^2) / (2.998 x 10^8 m/s)
= 1.37 x 10^(-6) N
The area of the card is
= 15 cm x 30 cm = 450 cm^2
= 4.50 x 10^(-2) m^2,
so the force per unit area (pressure) exerted on the card by the radiation is:
= P = 1.37 x 10^(-6) N / 4.50 x 10^(-2) m^2
= 3.04 x 10^(-4) N/m^2
Therefore, the force exerted on the card by the radiation is 3.04 x 10^(-4) N/m^2.
To know more about radiation please refer: https://brainly.com/question/13934832
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