Hi Ankodia,
Kindly mention a video time or share your work if you have some doubt in solving a question.
Yes.
Kindly mention the question number or share a snap of question.
In Question 240,
According to Neil Bohr's Atom Model,
Since, the negatively charged electron revolves around a positively charged nucleous in circular orbit of radius r.
So, the revolving electron in a closed path will constitute an electric current. The motion of the electron in anticlockwise direction produces conventional current in the clockwise direction.
By definition of electric current, we write the expression for current
Here, e is the charge of electron and T is the time period in which the electron completes one revolution.
Now, let's take v as the orbital velocity of the electron, then
Hence,
The orbital magnetic moment μ can be calculated now using formula below (You may have studied in Electrostatics Unit of Physics-XII)
Here, I is the current and A is the area of surface.
Thus, we get the value of magnetic moment
In above equation we have written (mvr) in terms of angular moment (p), since angular moment is equal to mvr.
Now, According to Bohr's model we know that
Hence, you can see from above equation of magnetic moment that it is proportional to n (the quantum number.)
In question 239,
For any orbital, we know the total energy of the electron by following formula (Watch video #2 of this chapter at 19:30-21:00).
Here, we already know that Z is 1 for Hydrogen atom and n is the number of orbital.
Now we already know the ratio of KE and PE with respect to total energy. (Please watch the video #2 of this chapter again at 18:00-19:00).
Using that relation you will be able to find the answer of this question.
Hope it helps your concern.