Given below are two statements: Statement I: Electromagnetic waves carry energy as they travel through space and this energy is equally shared by the electric and magnetic fields. Statement II: When electromagnetic waves strike a surface, a pressure is exerted on the surface. In the light of the above statements, choose the most appropriate answer from the options given below:

Both Statement I and Statement II are correct.

Statement I is incorrect but Statement II is correct.

Statement I is correct but Statement II is incorrect.

Both Statement I and Statement II are incorrect.

Electromagnetic Waves PYQ — JEE Main 2024 · 31 Jan · Shift 2 · Q61 with Solution

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Correct answer: B

Analyze Statement I

Electromagnetic waves carry energy through space. The energy density in an electromagnetic wave is $u = u_E + u_B = \frac{1}{2}\varepsilon_0 E^2 + \frac{1}{2\mu_0} B^2.$

For a plane electromagnetic wave in free space, $E = cB.$ Using $c^2 = \frac{1}{\mu_0 \varepsilon_0}$ , $\frac{1}{2\mu_0}B^2 = \frac{1}{2\mu_0}\left(\frac{E}{c}\right)^2 = \frac{1}{2}\varepsilon_0 E^2.$

Hence, $u_E = u_B.$

So, the energy is equally shared by electric and magnetic fields.

Therefore, Statement I is correct.
Analyze Statement II

Electromagnetic waves carry momentum as well as energy. When they strike a surface, they exert radiation pressure.
- For a perfectly absorbing surface, pressure is $P = \frac{I}{c}.$
- For a perfectly reflecting surface, pressure is $P = \frac{2I}{c}.$
Therefore, Statement II is correct.
Choose the correct option

Since both Statement I and Statement II are correct, the correct option is: $\boxed{\text{B}}$
Compare with stored correct answer

Stored correct answer: B

Our derived answer matches the stored answer.

View written solutionFree

Correct answer: B

Analyze Statement I

Electromagnetic waves carry energy through space. The energy density in an electromagnetic wave is $u = u_E + u_B = \frac{1}{2}\varepsilon_0 E^2 + \frac{1}{2\mu_0} B^2.$

For a plane electromagnetic wave in free space, $E = cB.$ Using $c^2 = \frac{1}{\mu_0 \varepsilon_0}$ , $\frac{1}{2\mu_0}B^2 = \frac{1}{2\mu_0}\left(\frac{E}{c}\right)^2 = \frac{1}{2}\varepsilon_0 E^2.$

Hence, $u_E = u_B.$

So, the energy is equally shared by electric and magnetic fields.

Therefore, Statement I is correct.
Analyze Statement II

Electromagnetic waves carry momentum as well as energy. When they strike a surface, they exert radiation pressure.
- For a perfectly absorbing surface, pressure is $P = \frac{I}{c}.$
- For a perfectly reflecting surface, pressure is $P = \frac{2I}{c}.$
Therefore, Statement II is correct.
Choose the correct option

Since both Statement I and Statement II are correct, the correct option is: $\boxed{\text{B}}$
Compare with stored correct answer

Stored correct answer: B

Our derived answer matches the stored answer.