Calculating Energy of Photon in N = 3 to N = 2 Transition

[Thwin]

Homework Statement

What is the energy in electron volts of the photon emitted in the transition from level N = 3 to N = 2?
Nf=3
Ni=1

Homework Equations

$$\frac{-13.6}{N^{2}}$$
-13.6(1/nf^2-1/ni^2)
also try -13.6/(nf^2-ni^2)

The Attempt at a Solution

i did -13.6(1/3^2-1/2^2)=1.888
and also try -13.6/(3^2-2^2)=-2.72
im not sure where i go wrong maybe it is the sign or something but i only have one chance left.

 

[anathema]

it is important to always double check your calculations and make sure you are using the correct equations. In this case, the correct equation to use is -13.6(1/nf^2-1/ni^2), which you have used in your first attempt. However, the values of Nf and Ni should be 3 and 2 respectively, since those are the levels given in the problem. Therefore, the correct calculation would be -13.6(1/3^2-1/2^2) = 1.89 eV. It is important to pay attention to the units as well, as electron volts (eV) is the correct unit for energy in this case. I hope this helps and good luck on your final attempt!