Calculating the Speed of a 796eV Electron

In summary, the conversation discusses finding the speed of a 796eV electron using the equations E = hc/lambda and E = hv. The participants of the conversation struggle with unit conversions and solving for the correct value of velocity. After some attempts and suggestions, they eventually figure out the correct conversion and solve for the velocity to be 4.18E16 m/s.
  • #1
skibum143
112
0

Homework Statement



What is the speed of a 796eV electron?

Homework Equations



E = hc/lambda
E = hv

The Attempt at a Solution



I'm not sure how to get a value for meters... I know if I take h (plank's constant) and divide the electron, I will get 4.14E-15 ev*s / 796 eV = 5.20E-18 seconds, but that is just a time, i don't know how to get the distance for that time...
 
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  • #2
That energy is entirely kinetic.

Ek=1/2 mv2
 
  • #3
If 796 = 1/2 * 9.11E-31 * v^2, I get v to be 4.18E16 m/s which is wrong...i'm not sure what I'm doing wrong...
 
  • #4
Watch your units.
 
  • #5
I tried converting eV to joules, which gave me 1.27E-16 joules, which gave me 8.36E6 m/s but that is wrong too. I think the units for mass (kg) are correct, I'm not sure what I have wrong...
 
  • #6
Check your math.
 
  • #7
For:
796 = 1/2 * mv^2 (where m = 9.11E-31) I keep getting 4.18E16 for v

I don't understand what part I'm doing wrong, I've done it about ten times...
 
  • #8
Show how you solved for v.

--
 
  • #9
eV = 1/2 mv^2
eV / (1/2m) = v^2
v = sqrt (eV / 1/2m)

Am I doing this wrong?
 
  • #10
So far OK.

Seems to me like somehow you are misplacing 2 when calculating value.
 
  • #11
I'm using
m = 9.11E-31
eV = 796

796 = 1/2*9.11E-31 v^2
796 = 4.55E-31 v^2
1.748E33 = v^2
v = 4.18E16

Don't know where I'm wrong...
 
  • #12
Seems like my guess was wrong. You have ignored my earlier remark about using correct units. Sigh.
 
  • #13
I didn't ignore it, I don't understand where my units are wrong. eV, m = kg

If you would tell me which part I'm doing wrong I could try and fix it.
 
  • #14
Nevermind, I got it myself. I was using the wrong value to convert eV. Thanks anyway
 
  • #15
skibum143 said:
I didn't ignore it, I don't understand where my units are wrong. eV, m = kg

You have to convert eV to J, from what you wrote you were assuming 796 [eV] = 1/2 9.11E-31 [kg] * x2 [m/s]2. eV is NOT kg*m2*s-2, it is about 1.602e-19 kg*m2*s-2 (or 1.602e-19 J).
 

1. What is the speed of a 796eV electron?

The speed of a 796eV electron can be calculated by using the formula v = √(2E/m), where v is the speed in meters per second, E is the energy in electron volts, and m is the mass of the electron in kilograms. Plugging in the values, we get a speed of approximately 5.4 x 10^6 meters per second.

2. How is the speed of an electron with 796eV energy determined?

The speed of an electron with 796eV energy is determined by using the equation v = √(2E/m), where v is the speed, E is the energy, and m is the mass of the electron. The energy of the electron can be determined through various methods such as measuring its kinetic energy or using a particle accelerator.

3. Does the speed of a 796eV electron change in different environments?

The speed of a 796eV electron is a constant value and does not change in different environments. However, the electron may experience changes in its path due to interactions with other particles or electromagnetic fields in the environment.

4. How does the speed of a 796eV electron compare to the speed of light?

The speed of a 796eV electron, which is approximately 5.4 x 10^6 meters per second, is significantly slower than the speed of light, which is approximately 3 x 10^8 meters per second. This is due to the fact that the mass of an electron is much smaller than the mass of a photon, which is the particle that makes up light.

5. What is the significance of the speed of a 796eV electron?

The speed of a 796eV electron is significant in understanding the behavior of particles at high energies. It is also important in various fields such as nuclear physics, particle physics, and materials science. Understanding the speed of electrons at different energy levels can help in the development of new technologies and advancements in scientific research.

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