Below are the choices that can be found from other source:
a. frequency
b. the Doppler effect
c. the resonance effect
<span>d. intensity
The answer is B.
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Answer:
The energy in its ground state is 10 meV.
Explanation:
It is given that,
The energy of the electron in its first excited state is 40 meV.
Energy of the electron in any state is given by :
For ground state, n = 1
.............(1)
For first excited state, n = 2
.............(2)
Dividing equation (1) and (2), we get :
So, the energy in its ground state is 10 meV. Hence, this is the required solution.
Answer: 500 s
Explanation:
Speed 
is defined as a relation between the distance 
and time 
:
Where:
is the speed of light in vacuum
is the distance between the Earth and Sun
is the time it takes to the light to travel the distance
Isolating :
Finally:
'The normal is a line perpendicular to the surface of the mirror'.This is the correct statement that corrects an error on the site.
<h3>What is the law of reflection?</h3>
The law of reflection specifies that upon reflection from a downy surface, the slope of the reflected ray is similar to the slope of the incident ray.
The reflected ray is consistently in the plane determined by the incident ray and perpendicular to the surface at the point of reference of the incident ray.
When the light rays descend on the smooth surface, the angle of reflection is similar to the angle of incidence, also the incident ray, the reflected ray, and the normal to the surface all lie in a similar plane.
Hence 'The normal is a line perpendicular to the surface of the mirror'.This is the correct statement that corrects an error on the site
To learn more about the law of reflection refer to the link;
brainly.com/question/12029226
