## Midterm Question 3B

$c=\lambda v$

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### Midterm Question 3B

For midterm question 3B, can someone explain it to me? I keep getting down to the last few steps and messing it up.

Thank you!!

Julia Go 2L
Posts: 60
Joined: Sun Sep 30, 2018 12:17 am
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### Re: Midterm Question 3B

We can use the equation I = hv - 1/2mV^2 to solve this problem.

Since hv= hc/λ and λ = 58.4 x 10^-9 m we can calculate the energy of the incoming photon.

The mass we use in this equation is the mass of an election.
m= 9.109383 x 10^-31kg
The velocity is given but we need to convert it to SI Units:
2450 km/s = 2450 x 10^3 m/s

When everything is plugged in correctly, you should get I= 6.67498 x 10^-19 J
Since there are 3 significant figures in the question, we round the answer to 6.67 x 10^-19 J