Which one of the following will not generate electromagnetic waves or pulses? a

Question

Which one of the following will not generate electromagnetic waves or pulses? a steady direct current an accelerating electron a proton in simple harmonic motion an alternating current charged particles traveling in a circular path in a mass spectrometer A television station broadcasts at a frequency of 86 MHz. The circuit contains an inductor with an inductance L = 1.2 times 10^-6 H and a variable-capacitance C. Determine the value of C that allows this television station to be tuned in 2.9 times 10^-12 F 1.8 times 10^-11 F 1.1 times 10^-10 F 5.8 times 10^-12 F 3.6 times 10^-11 F If the radiant energy front the sun comes in as a plane electromagnetic wave of average intensity 1340 W/m^2, calculate the peak value of B. 2.90 times 10^-4 T 6.70 times 10^-6 T 1.67 times 10^-6 T 5.80 times 10^-4 T 3.35 times 10^-6 T If the radiant energy from the sun comes in as a plane electromagnetic wave with a peak value of B of 1.67 times 10^-6 T, calculate the peak value of E. 500 V/m 2.0 kV/m 170 kV/m 1.0 kV/m 87 kV/m An astronomer observes electromagnetic waves emitted by oxygen atoms in a distant galaxy that have a frequency of 5.710 times 10^14 Hz. In the laboratory on earth, oxygen atoms emit waves that have a frequency of 5.814 times 10^14 Hz. Determine the relative velocity of the galaxy with respect to the astronomer on earth. 6.724 times 10^6 m/s, away from earth 4.369 times 10^4 m/s, toward earth 6.724 times 10^6 m/s, toward earth 4.369 times 10^4 m/s, away from earth 5.366 times 10^6 m/s, away from earth

Explanation / Answer

1.(a) Steady Direct Current

A direct current will generate a magnetic field but since the charge carriers are not accelerating there will be no electromagnetic waves or pulses

2. The resonant frequency of tuned LC circuit is given as

     f0 =1/2LC

     f02 =1/42LC

      or C =1/42Lf02

              =1/42(1.2*10-6H)(86*106Hz)2

               = 2.8540*10-12 F

                = 2.9*10-12 F

3. Given Data

Intensity : I = 1340 W/m²
We have permeability : µo = 4p x 10^-7 T•m/A
speed of light : c = 3 x 10^8 m/s

To Calculate the peak values of B : (Bm - Max magnetic field)
use formula : I = (c Bm²) / (2 µo)
=> 1340 = (3 x 10^8 x Bm²) / (2 x 4pi x 10^-7)
=> 1340 = (3 x 10^8 x Bm²) / (25.12 x 10^-7)
=> (3 x 10^8 x Bm²) = 1340 x (25.12 x 10^-7)
=> (3 x 10^8 x Bm²) = 3.366 x 10^-3
=> Bm² = 3.366 x 10^-3 / 3 x 10^8
=> Bm² = 1.122 x 10^-11
=> Bm = 3.35 x 10^-6 Tesla

4. Given Data

Peak value of B, i.e Bm = 1.67x10^-6 T

We have
speed of light : c = 3 x 10^8 m/s
To calculate the peak values of E : (electricity field)

use formula : Em = c x Bm
=> Em = (3 x 10^8) (1.67x10^-6)
=> Em = 501 N/C = 501 V/m = 500 V/m

5. Vrel = [ ( F(Source) - F(observed) ) / (2*F(Source)) ] * 2c
   Vrel = [(5.710*10^14 - 5.841*10^14)/(2*5.841*10^14)] * 2*(2.9979 *10^8)
         = 6728299.949 m/s
       = 6.724 * 10^6 m/s traveling away from the Earth

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