E2−E2hc\dfrac{E_{2}-E_{2}}{h c}hcE2−E2
hcE2−hcE1\dfrac{\mathrm{hc}}{\mathrm{E}_{2}}-\dfrac{\mathrm{hc}}{\mathrm{E}_{1}}E2hc−E1hc
ch(E2−E1)\dfrac{c}{h\left(E_{2}-E_{1}\right)}h(E2−E1)c
hc E2−E1\dfrac{\text { hc }}{E_{2}-E_{1}}E2−E1 hc