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erik [133]
3 years ago
14

The magnitude of the Poynting vector of a planar electromagnetic wave has an average value of 0.724 W/m^2. What is the maximum v

alue of the magnetic field in the wave?
a. 77.9 nT
b. 55.1 nT
c. 38.9 nT
d. 108 nT
Physics
2 answers:
alexira [117]3 years ago
8 0

Answer:

a. 77.9 nT

Explanation:

Given;

average value of the electromagnetic wave, E = 0.724 W/m^2

The average value of a Poynting vector is given by;

S = \frac{1}{2\mu_o} *E_oB_o\\\\But, E_o = cB_o\\\\S = \frac{1}{2\mu_o} *cB_o^2\\\\cB_o ^2= 2\mu_o S\\\\B_o^2 = \frac{2\mu_o S}{c}\\\\B_o = \sqrt{ \frac{2\mu_o S}{c}} \\\\B_o =   \sqrt{ \frac{2(4\pi*10^{-7}) (0.724)}{3*10^8}}\\\\B_o = 7.79*10^{-8} \ T\\\\B_o = 77.9*10^{-9} \ T\\\\B_o = 77.9 \ nT

Therefore, the maximum value of the magnetic field in the wave is 77.9 nT.

Gala2k [10]3 years ago
5 0

Answer:

A I think : )

Explanation:

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Answer:

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Explanation:

Time taken by the tennis ball to reach maximum height, t = 0.5 x 7 = 3.5 seconds.

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Equation of motion result we have v = u + at

Substituting

             0 = u - 9.81 x 3.5

             u = 34.335 m/s

Velocity of throwing = 34.335 m/s

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Which device or set of devices is contained in a mobile telephone?
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The motivation for Isaac Newton to discover his laws of motion was to explain the properties of planetary orbits that were obser
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Answer:

a)  v² = G M R³,  b)  T = 2π /\sqrt{GMR}, c)  m \sqrt{GMR^5 }

Explanation:

a) The kinetic energy is

         K = ½ m v²

       

to find the velocity let's use Newton's second law

          F = m a

acceleration is centripetal

           a = v² / R

           

force is the universal force of attraction

           F = G m M / r²

we substitute

          G m M R² = m v² R

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b) angular and linear velocity are related

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          w = \sqrt{GMR}

the angular velocity is related to the period

          w = 2π / T

          T = 2π / w

we substitute

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c) the angular moeomto is

            L = m v r

            L = m RA G M R³ R

            L =  m \sqrt{GMR^5 }

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