Answer:
<h2>c. remain constant</h2>
Explanation:
Such type of field that is created by the magnetic condition is known as magnetic field. Such type of the developed by electrical condition and some other ways. This filed has many important roles in electrical engineering and some other fields.
When any magnetic field acts in perpendicular condition then no work is done by the field. Thus the kinetic energy and speed of the particle remain in constant condition.
The number of lines per mm in the diffraction grating is 326.
<h3>What is diffraction grating?</h3>
A diffraction grating is a type of optical instrument obtained with a continuous pattern. The pattern of the diffracted light by a grating depends on the structure and number of elements present.
The given data in the problem is
is the angle formed between the path of the incident light and the diffracted light = 9. 2°
λ is the wavelength of the light=490nm=4.9
N is the number of lines per mm in the diffraction grating=?
n is ordered = 1
The formula for the diffraction grating is;

The number of lines per mm is found as;

Hence the number of lines per mm in the diffraction grating is 326.
To learn more about diffraction grating refer to the link;
brainly.com/question/1812927