Answer:
Explanation:
When 238U which is radioactive turns into 206Pb , it becomes stable and no further disintegration is done . Hence in the initial period ratio of 238U undecayed and 206Pb formed will be very high because no of atoms of 238U in the beginning will be very high. Gradually number of 238U undecayed will go down and number of 206Pb formed will go up . In this way the ratio of 238U and 206Pb in the mixture will gradually reduce to be equal to one or even less than one .
In the given option we shall calculate their raio
1 ) ratio of 238U and 206Pb = 5
2 ) ratio of 238U and 206Pb = 4
3 )ratio of 238U and 206Pb = 1
4 ) ratio of 238U and 206Pb = 20
5 )ratio of 238U and 206Pb = 3
lowest ratio is 1 , hence this sample will be oldest.
Ranking from youngest to oldest
4 , 1 , 2 , 5 , 3 .
Answer:
Work function of the metal is 3.24 eV.
Explanation:
It is given that,
Wavelength, 
Let W is the work function of the metal. It is given by using Einstein's photoelectric effect equation. It is given by :
Since, 
So, W = 3.24 eV
So, the work function of the metal is 3.24 eV. Hence, this is the required solution.
B) Distance: the farther, the weaker!
The infrared<span> (</span>IR<span>) and the </span>ultraviolet(UV<span>) represent the two extremities of the visible spectrum (400-700nm). While </span>IR<span> represents electromagnetic radiation
with wavelengths longer than those of visible </span>light<span>, </span>UV<span> represents wavelengths
shorter than visible </span>light<span>.
</span><span>
</span>
Answer:
A microwave
Explanation
The human retina can only detect incident light that falls in waves 400 to 720 nanometers long, so we can't see microwave or ultraviolet wavelengths. This also applies to infrared lights which has wavelengths longer than visible and shorter than microwaves, thus being invisible to the human eye.
