Answer:
a). 87.5 mA or
A
b). 1.78 
Explanation:

n the number of free electrons is 28 in text reference and if they don't give q is take as the charge of electron.
a).
A
b).


Все написано в скобках правильно
Answer:
145 m
Explanation:
Given:
Wavelength (λ) = 2.9 m
we know,
c = f × λ
where,
c = speed of light ; 3.0 x 10⁸ m/s
f = frequency
thus,

substituting the values in the equation we get,

f = 1.03 x 10⁸Hz
Now,
The time period (T) = 
or
T =
= 9.6 x 10⁻⁹ seconds
thus,
the time interval of one pulse = 100T = 9.6 x 10⁻⁷ s
Time between pulses = (100T×10) = 9.6 x 10⁻⁶ s
Now,
For radar to detect the object the pulse must hit the object and come back to the detector.
Hence, the shortest distance will be half the distance travelled by the pulse back and forth.
Distance = speed × time = 3 x 10^8 m/s × 9.6 x 10⁻⁷ s) = 290 m {Back and forth}
Thus, the minimum distance to target =
= 145 m
Rosalind Franklin, James Watson, and Francis Crick’s discovered the DNA's Double Helix.
<h3>What is DNA?</h3>
DNA is an abbreviation for deoxyribonucleic acid and it can be defined as the molecules that are found within cells, and they are saddled with the responsibility of storing genetic information in living organisms.
In 1953, James Watson and Francis Crick's used other scientists' work to create a model of DNA in that they used Rosalind Franklin's photo to help them determine that deoxyribonucleic acid (DNA) was a double helix.
Furthermore, the discovery of DNA's Double Helix by Rosalind Franklin, James Watson, and Francis Crick led to modern molecular biology, which has helped many scientists and researcher to understand how genes control the chemical processes in the body of a living organism.
Read more on DNA's Double Helix here: brainly.com/question/26733817
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