J.J. Thomson discovered electrons and noticed that an atom can be divided. Also, he concluded atoms are made of positive cores and negatively charged particles within it.
Answer : Relatively hot objects
Explanation : We know that, the temperature of the objects is inversely proportional to their wavelengths. The objects emitting radiation in the visible region have short wavelength and hence are relatively hotter.
We know the range of wavelength of the visible spectrum is from 400 nm to 780 nm.
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Answer:
So the ratio will be 
Explanation:
We have given heat engine absorbs 450 joule from high temperature reservoir
So 
As the heat engine expels 290 j
So work done W = 290 J
We know that efficiency 
It is given that efficiency of the engine only 55 % of Carnot engine
So efficiency of Carnot engine 
Efficiency of Carnot engine is 
The amount of gold in decigrams if 450 micrograms is needed is 4.5 × 10-³ decigrams.
<h3>How to convert micrograms to decigrams?</h3>
According to this question, 450 micrograms of a sample of gold is needed but we only have a mass balance that measures in decigrams.
This means that we are to convert the amount of gold you need to decigrams by comparing the exponents.
The conversion factor of micrograms to decigrams is as follows:
1 micrograms = 1 × 10-⁵ decigrams
This means 450 micrograms is equivalent to 450 × 1 × 10-⁵ = 4.5 × 10-³ decigrams
Therefore, the amount of gold in decigrams if 450 micrograms is needed is 4.5 × 10-³ decigrams.
Learn more about decigrams at: brainly.com/question/6869599
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