An excited atom can return to its ground state by absorbing electromagnetic radiation is false about the electromagnetic radiation.
Option B
<u>Explanation</u>:
In the scope of modern quantum theory, the term Electromagnetic radiation is identified as the movement of photons through space. Almost all the sources of energy that we utilize today such as coal, oil, etc are a product of electromagnetic radiation which was absorbed from the sun millions of years ago.
Various properties of electromagnetic radiations are a directly proportional relationship between the energy and the frequency, Inverse proportionality between frequency and the wavelength, etc. Hence, we can conclude that an "excited atom" can never return to its ground state by assimilating electromagnetic radiation and the 2nd statement is false.
Answer:(a)360N,(b)171N,(c)2.702m
Explanation:
(a)Maximum Friction Force =
=360 N


(b)Moment about Ground Point




(c)

Here maximum friction force can be 360 N
Therefore 
Where x is the maximum distance moved by man along the ladder

740x=2000
x=2.702m
Answer:
1000 Hz
Explanation:
<em>The frequency would be 1000 Hz.</em>
The frequency, wavelength, and speed of a wave are related by the equation:
<em>v = fλ ..................(1)</em>
where v = speed of the wave, f = frequency of the wave, and λ = wavelength of the wave.
Making f the subject of the formula:
<em>f = v/λ.........................(2)</em>
Also, speed (v) = distance/time.
From the question, distance = 900 m, time = 3.0 s
Hence, v = 900/3.0 = 300 m/s
Substitute v = 300 and λ = 0.3 into equation (2):
f = 300/0.3 = 1000 Hz