Line spectra are obtained when individual elements are heated using a high-voltage electrical discharge. This heating causes excitation of the element and a subsequent emission of distinct lines of colored light are obtained. Each element has its own unique emission line spectrum; therefore, if any of the tested substances were the same, their spectra would match. However, this is not the case so none of the substances are the same.
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Answer:
a) E = 0
b) 
Explanation:
The electric field for all points outside the spherical shell is given as follows;
a) 
From which we have;
E = 0/A = 0
E = 0
b)
By Gauss theorem, we have;
Therefore, we get;
The electrical field outside the spherical shell
Therefore, we have;
Answer: Not 100% sure but I believe the answer is B.
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Answer:
<span>GPE=81000J or 81kJ</span>
Explanation
Potential Energy = mgh = 20 x 9.8 x ?
<span>To find H use one of the equation of motion </span>
<span>= [(90)^2 - 0 ] / 2(9.8) </span>
<span>Potential Energy = mgh = 20 x 9.8 x 8100 /2(9.8) = 81000 J</span>
