Which of these will create EM radiation? a. an electron moving at constant velocity b. an electron moving at a constant speed in a circular path c. a motionless proton d. an AC circuit e. a proton moving at a constant speed in a circular path

B) an electron moving at a constant speed in a circular path

D) an AC circuit

E) a proton moving at a constant speed in a circular path

Explanation:

In classical physics, the EM radiation is generated by accelerated charges. Due to that, electrons with constant velocity do not produce EM. However, charges with a circular motion, even with a constant speed, will generate EM because of the centripetal acceleration.

Hence, the following will generate EM

b) an electron moving at a constant speed in a circular path c

d) an AC circuit (because the electrons are accelerated frequently in a sinusoidal signal)

e) a proton moving at a constant speed in a circular path

hope this helps!!

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.