Answer: 5 → 2
Explanation: An electron when given enough energy will get excited to the higher states and when it returns to the ground state will emit energy in the from of light.
The most energetic energy level will be 5 → 2 because in this, energy level 2 is the ground state and energy level 5 is the excited state . Thus more energy will be needed by the electron to move towards the higher excited state.
The energy required by the 4 → 2 energy level will be of medium level and
3 → 2 will require the least energy.
The image for the reference is shown below.
Well they can be used to make electromagnets that can power a lot of things like door bells and if you have a large not like the size of a fist larger enough to power a house or a decent sized building.
So we know that there are two types of electric currents AC and DC. (AC-DC). The flowing electrons produce something called a magnetic field and the spinning magnets cause Electric current to flow between copper wire.
Example time!
Take a battery, copper wire, and a magnet. Battery connection thing. So place the battery at the bottom put the magnet on top. With the copper wire put it into loops and when place above the battery and magnet. Give it a slight push and it should spin because of the reaction