Plz check this question and solution also i am getting negative( change in energy) ex the frequency of radiation emitted10-4 js)

When you subtract more negative from less negative, you'll get a positive quantity...and that will be the energy of the radiation emitted.

Hope you understand. 😊

sir always we have to subtract like this ...E 4-E1 buy in some cases for example excitation energy for going n=1 to n=2;is E 2 -E1

?

Depends on question, Shweta!

It depends what is asked in the question...you can't have radiation of negative frequency so, you have to apply yourself accordingly... generally, we are asked of the energy difference basically...that's why we subtract initial from final..but, the language of question can be changed! 😊 Hope it helped.

sir but I am getting energy value in negative

see

Shweta...in book it is taken E4-E1 so it comes positive...but you take E1-E4 so negative....both have same magnitude only sign is reversed

change in energy means energy gap magnitude is always same...

ok

ok

sir

but sir in book they have taken E4-E1 why

shweta in various sites you see they get negative values too...

wait i m sending you references

https://socratic.org/questions/the-frequency-of-radiation-emitted-when-electron-falls-from-n-4-to-n-1-in-a-hydr check shweta

Magnitude always remain same and in option also you don't get option in negative n positive with same magnitude

one magnitude one option only

ok

and in case of going lower to higher then also we take positive value

shweta in various energy level you know how much energy is there...means -13.6....and so on upto higher energy level...so according to question...absorption or emission then you proceed