Question

What is the energy (in joules) of an ultraviolet photon with wavelength 90 nm ?

Answer 1

energy can be calculated using this formula

E=hc/ λ

, we have λ=100 nm=10^(-7)

c=3 × 108

AND h=6.626 × 10 −34

therefore using this in above formula

E =(6.626 × 10 −34) × (3 × 108)/10^(-7)

=>19.828 ×10^(-34+8+7)

=>19.828× 10^(-19)

=>1.9828×10^(-20)J

in two significant figures ans is

2.0 ×10^(-20)

or 1.9 × 10^(-20)

,and

you can calculate frequency by using

E=hv

1.9×10(-20)=6.626 × 10 −34 × v

v=0.28674917×10^(-20+34)

v=.28×10^(14)

or v= 2.8×10^(13)Hz