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3 years ago

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Which of the following statements is true? A. Matter requires energy to move and change. B. Energy cannot change from one type t

o another. C. Energy must remain where it is created. D. It is not possible to store energy for later use.

1 answer:

Naily [24]3 years ago

3 0

A. True. Matter requires energy to move and change.

B. False. Energy CAN change from one type to another. (Like changing the chemical energy in gasoline to kinetic energy of a moving car.)

C. False. Energy need not remain where it is created. (Like generating it in an electric power station and shipping it to your house to run your hair dryer.)

D. False. It IS possible to store energy for later use. (Like in a battery.)

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$f=\frac{3.0\cdot 10^8 m/s}{4.1 m}=7.32\cdot 10^7 Hz$

(b) $4.60\cdot 10^8 rad/s$

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For this wave,

$f=7.32\cdot 10^7 Hz$

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The angular wave number of a wave is given by

$k=\frac{2\pi}{\lambda}$

where

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B is the magnitude of the magnetic field component

For this wave,

E = 310 V/m

So we can re-arrange the equation to find B:

$B=\frac{E}{c}=\frac{310 V/m}{3\cdot 10^8 m/s}=1.03\cdot 10^{-6}T$

(e) z-axis

In an electromagnetic wave, the electric field and the magnetic field oscillate perpendicular to each other, and they both oscillate perpendicular to the direction of propagation of the wave. Therefore, we have:

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$I=\frac{E^2}{2\mu_0 c}$

where we have

E = 310 V/m is the amplitude of the electric field

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A = 1.8 m^2

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