Not sure if this is what you’re looking for. Let me know if I can clarify anything.
when we need to represent the magnetic field in a specific region where it is given that magnetic field lines are perpendicular to the plane and going inside the plane then we always use the concept of representation by "X"
here this symbol represents that field lines are going into the plane
it is also the uniform magnetic field always
so the correct answer would be
<u>Magnetic Field</u>
Answer:
the only one of these materials that allows studying processes of a very long period of time is Uranium 238
Explanation:
In a radioactive material, half of the atoms decay each life period, in carbon 14 this period T = 5730 years, so for a time of 40,000 years there are 7 life periods, so there are very few atoms left without decomposing .
To study older samples, materials with a longer life period are needed, let's show the visa time
²³⁸U T= 4.5 10¹⁰ years
⁹¹Rb T = 58 s
¹³¹I T= 8.04 days
⁶⁰Co T= 5.27 years
Therefore, the only one of these materials that allows studying processes of a very long period of time is Uranium 238
