Question

1. What is the momentum of a photon of light that has a frequency of 2.9 x 10^14 Hz?

a) 1.5 x 10^-28 kg m/s

b) 2.1 x 10^-28 kg m/s

c) 4.4 x 10^-28 kg m/s

d) 6.3 x 10^-28 kg m/s

e) 6.2 x 10^-28 kg m/s

ANSWER E

2. What is the momentum of a photon of light that has a wavelength of 480nm?

a) 1.1 x 10^-27 kg m/s

b) 2.2 x 10^-27 kg m/s

c) 1.8 x 10^-27 kg m/s

d) 1.4 x 10^-27 kg m/s

e) 2.0 x 10^-27 kg m/s

ANSWER: D

Answer 1

1) Lets, frequency = 2.9×10^14 Hz

wavelength = L

and speed of light = c

momentum = p

planks constant = h

So, We know that;

frequency = c/ L

  L = c/f.....................................1

And wavelength = h/ momentum

  c/f = h/p

  f/c = p/h

p = hf/c ..................................2

  c = 3×10^8, , h = 6.6×10^-34 , f=frequency of 2.9 x 10^14 Hz

then,

  p = hf/c ..................................2

  

   Option D is correct answer =

2)

   wavelength of =480 nm

It could be calculated using De-broglie equation:  p = h / λ ,

  

.....................................(3)

Where,

λ = wavelength of light.

From equation (3)

  

  

Option D IS correct answer