2012 HSC MC q20 (1 Viewer)

[Sheepishly]

Um can someone explain to me why it is B?

 

[Dementured]

bump

 

[HowToNoob101]

First you estimate the peak wave length (8x10^-6), then using C=fλ work out the frequency: f = 3x10^8/8x10^-6
Then using the formula E=hf to find out the energy: E=3.75x10^13 x 6.626x10^-34
Then divide by 1.602x10^19 to convert from J to eV.
Answer = 0.155 which B is the closest.