Question

Place the following in terms of increasing energy:

a photon of 1 picojoule energy

1 cm wavelength

1 million Hz

visible light

Answer 1

1)
E1 = 1 PJ = 1*10^-12 J

2)

Given:
lambda = 1*10^-2 m

use:
E = h*c/lambda
=(6.626*10^-34 J.s)*(3.0*10^8 m/s)/(1*10^-2 m)
= 1.988*10^-23 J
Answer: 2.0*10^-23 J

3)

Given:
f = 1*10^6 s-1

use:
E = h*f
=(6.626*10^-34 J.s)*(1*10^6) s-1
= 6.6*10^-28 J

4)

average wavelength of visible light is
lambda = 6*10^-7 m

use:
E = h*c/lambda
=(6.626*10^-34 J.s)*(3.0*10^8 m/s)/(6*10^-7 m)
= 3.3*10^-19 J

So, order of increasing energy is:
1 million Hz < 1 cm wavelength < visible light < a photon of 1 picojoule energy