A plane electromagnetic wave varies sinusoidally at 81.4 MHz as it travels through vacuum along the positive x direction. The peak value of the electric field is 2.12 mV/m, and it is directed along the positive y direction. (a) Find the wavelength. 3.69 ✔m (b) Find the period. 12.3 ✔ns (c) Find the maximum value of the magnetic field. 7.07 ✓ PT pT (d) Write expressions in SI units for the space and time variations of the electric field. (x is in meters, and t in seconds.) E = (2.12E-3 ✓) cos 2x( x magnitude Did you accidentally divide or take the inverse in your calculation?x - 81.4E6 direction +y Write expressions in SI units for the space and time variations of the magnetic field. (x is in meters, and t in seconds.) B = (7.07E-12✔ ) cos 2л( [ x Did you accidentally divide or take the inverse in your calculation?x - 81.4E6 ✔ t) magnitude direction +z (e) Find the average power per unit area this wave carries through space. 5.97E-9 W/m² t) (f) Find the average energy density in the radiation. 2E-17 J/m3 (g) What radiation pressure would this wave exert upon a perfectly reflecting surface at normal incidence? x Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully. Pa

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### Electromagnetic Wave Properties

A plane electromagnetic wave varies sinusoidally at 81.4 MHz as it travels through a vacuum along the positive x-direction. The peak value of the electric field is 2.12 mV/m, and it is directed along the positive y-direction.

#### (a) Calculating the Wavelength
- **Wavelength**: 3.69 m ✔️

#### (b) Finding the Period
- **Period**: 12.3 ns ✔️

#### (c) Maximum Magnetic Field
- **Maximum Magnetic Field**: 7.07 pT ✔️

#### (d) Expressions for Space and Time Variations

- Electric Field:
  \[
  E = (2.12 \times 10^{-3}) \cos 2\pi( \text{______} x - 81.4 \times 10^6 t)
  \]
  - **Direction**: +y ✔️

- Magnetic Field:
  \[
  B = (7.07 \times 10^{-12}) \cos 2\pi( \text{______} x - 81.4 \times 10^6 t)
  \]
  - **Direction**: +z ✔️

*Note: Check if divisions or inverses were applied correctly.*

#### (e) Average Power per Unit Area
- **Average Power per Unit Area**: 5.97E-9 W/m² ✔️

#### (f) Average Energy Density in Radiation
- **Average Energy Density**: 2E-17 J/m³ ✔️

#### (g) Radiation Pressure on a Reflective Surface
- **Radiation Pressure**: Incorrect; rework the calculation carefully.

*Ensure to revisit all steps if discrepancies appear in your solutions.*

This educational content outlines steps and calculations related to plane electromagnetic waves, helping students understand concepts of wave behavior in a vacuum, field variations, and energy dynamics.
Transcribed Image Text:### Electromagnetic Wave Properties A plane electromagnetic wave varies sinusoidally at 81.4 MHz as it travels through a vacuum along the positive x-direction. The peak value of the electric field is 2.12 mV/m, and it is directed along the positive y-direction. #### (a) Calculating the Wavelength - **Wavelength**: 3.69 m ✔️ #### (b) Finding the Period - **Period**: 12.3 ns ✔️ #### (c) Maximum Magnetic Field - **Maximum Magnetic Field**: 7.07 pT ✔️ #### (d) Expressions for Space and Time Variations - Electric Field: \[ E = (2.12 \times 10^{-3}) \cos 2\pi( \text{______} x - 81.4 \times 10^6 t) \] - **Direction**: +y ✔️ - Magnetic Field: \[ B = (7.07 \times 10^{-12}) \cos 2\pi( \text{______} x - 81.4 \times 10^6 t) \] - **Direction**: +z ✔️ *Note: Check if divisions or inverses were applied correctly.* #### (e) Average Power per Unit Area - **Average Power per Unit Area**: 5.97E-9 W/m² ✔️ #### (f) Average Energy Density in Radiation - **Average Energy Density**: 2E-17 J/m³ ✔️ #### (g) Radiation Pressure on a Reflective Surface - **Radiation Pressure**: Incorrect; rework the calculation carefully. *Ensure to revisit all steps if discrepancies appear in your solutions.* This educational content outlines steps and calculations related to plane electromagnetic waves, helping students understand concepts of wave behavior in a vacuum, field variations, and energy dynamics.
Expert Solution
Step 1: General expressions for Electric and Magnetic Fields

The electric field (E) and magnetic field (B) vary sinusoidally with space (x) and time (t). In SI units, they can be written as:

E left parenthesis x comma t right parenthesis equals E subscript 0 sin left parenthesis k x minus omega t right parenthesis

B left parenthesis x comma t right parenthesis equals B subscript 0 sin left parenthesis k x minus omega t right parenthesis

Where:
E subscript 0 is the maximum electric field, which is 2.12 cross times 10 to the power of negative 3 end exponent V/m in this case.

B subscript 0 equals E subscript 0 over cis the maximum electric field, which is 7.07 cross times 10 to the power of negative 12 end exponent T in this case.
k equals fraction numerator 2 pi over denominator lambda end fraction is the wave number, with lambda being the wavelength.
omega equals 2 pi f is the angular frequency, with f being the frequency.
c is the speed of light in a vacuum, 3 cross times 10 to the power of 8 m/s.

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