How to calculate wavelength electron given speed

In summary, the conversation discusses the use of equations 1/2 mv^2 and E = hf to calculate energy and frequency, and the need to use de Broglie's formula for matter waves. The final answer is 12 in an unspecified unit.
  • #1
Adam Rabe
33
0

Homework Statement


Unit conversion where did i go wrong.PNG

Homework Equations


1/2 mv^2
E = hf
c = f (wavelength)

The Attempt at a Solution


0.5 * (9.109 * 10^-31) * (6 * 10^4)^2 = energy
energy = hf => f = energy/(6.626*10^-34) = 2.47 * 10^12
wavelength (m) = (speed of light) / frequency
wavelength (m) * (1*10^9) = 121235.4

Answer is 12. What gives guys I am 4 decimal places too high is there some unit for any of the equations I am not getting?
Any help is greatly appreciated.
Adam
 
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  • #2
Adam Rabe said:

Homework Statement


View attachment 204156

Homework Equations


1/2 mv^2
E = hf

That formula is valid for photons. For matter waves, use de Broglie's formula for the wavelength.
Adam Rabe said:
Answer is 12. What gives guys I am 4 decimal places too high is there some unit for any of the equations I am not getting?
Any help is greatly appreciated.
Adam
12 in what units?
 
  • #3
ehild said:
That formula is valid for photons. For matter waves, use de Broglie's formula for the wavelength.

12 in what units?
omg i got it now. thanks a lot friend
 

FAQ: How to calculate wavelength electron given speed

1. What is the formula for calculating the wavelength of an electron given its speed?

The formula for calculating the wavelength of an electron is:
λ = h/mv
Where λ is the wavelength, h is Planck's constant (6.626 x 10^-34 J*s), m is the mass of the electron (9.11 x 10^-31 kg), and v is the speed of the electron.

2. How do I determine the speed of an electron?

The speed of an electron can be determined using the formula:
v = √(2KE/m)
Where v is the speed, KE is the kinetic energy of the electron, and m is the mass of the electron. Kinetic energy can be calculated using the formula KE = ½mv^2.

3. What units should I use when calculating the wavelength of an electron?

The units for wavelength are typically measured in meters (m). However, you can use other units such as nanometers (nm) or angstroms (Å) as long as you are consistent with your units throughout the calculation.

4. Can I calculate the wavelength of an electron if I only know its kinetic energy?

Yes, you can calculate the wavelength of an electron using the formula:
λ = h/√(2KE/m)
Where λ is the wavelength, h is Planck's constant, KE is the kinetic energy of the electron, and m is the mass of the electron.

5. Is the wavelength of an electron affected by its charge?

No, the wavelength of an electron is not affected by its charge. It is solely determined by its mass and speed, as shown in the formula λ = h/mv. The charge of an electron does not play a role in calculating its wavelength.

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