#1

I'm stuck on a particular question. Probably a simple solution but I can't seem to get it.

I know the Planck constant, charge on an electron, and the mass of an electron.

Any ideas?

**"Calculate the wavelength of electrons that have been accelerated from rest through a P.D. of 100V"**I know the Planck constant, charge on an electron, and the mass of an electron.

Any ideas?

#2

Google the problem, word for word. Works for 50-75% of my AP Chem homework.

#3

you lost me at "I'm"

#4

de Broigle equation might work

lamna = h/p

need to somehow find out the speed of the electron for it to work

lamna = h/p

need to somehow find out the speed of the electron for it to work

#5

^^

I stuck the values in this equation. Seemed to work.

EDIT- Yep, the de Broglie equation worked. You can replace 'p' (momentum) with-

root(2meV)

I stuck the values in this equation. Seemed to work.

EDIT- Yep, the de Broglie equation worked. You can replace 'p' (momentum) with-

root(2meV)

#6

There ya go then. lol

I don't remember much of electro/magnetism anymore... but I'm pretty sure the speed of an electron is usually at the speed of light?

I don't remember much of electro/magnetism anymore... but I'm pretty sure the speed of an electron is usually at the speed of light?

#7

It's accelerated through 100 electron volts so has 100 x electron rest mass of energy (I think) in Joules. Then E = hf (f = E/h) and lamda = c/f so lamda = (ch)/E. That's how I would do it. I think you use the rest mass of an electron for electron volts. Might wanna check it.

#8

i didnt even know electrons had a wavelength

#9

Google the problem, word for word. Works for 50-75% of my AP Chem homework.

That's because every AP test is put online and your teacher most likely just gives you old tests for homework.

#10

It's accelerated through 100 electron volts so has 100 x electron rest mass of energy (I think) in Joules. Then E = hf (f = E/h) and lamda = c/f so lamda = (ch)/E. That's how I would do it. I think you use the rest mass of an electron for electron volts. Might wanna check it.

aye that would work, but you might get marked down for the inaccuracy that an electron can approach but not reach c

#11

Meh it's a constant and I'm only AS standard so it'll do for me.

#12

ahh Physics is the devil's handy work

#13

That's because every AP test is put online and your teacher most likely just gives you old tests for homework.

No, they aren't all online, just most, and a large portion of our homework comes out of textbooks. APQ's aren't the only schoolwork answers you can find online.