### Planck's Constant

Posted:

**Sun Oct 15, 2017 8:50 pm**When would I need to use Planck's constant?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=14&t=22288

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Posted: **Sun Oct 15, 2017 8:50 pm**

When would I need to use Planck's constant?

Posted: **Sun Oct 15, 2017 9:00 pm**

whenever you need to use an equation with the constant "h" in it.

eg E=hv

good thing is, the value is on the formula sheet so we don't have to memorize it :)

eg E=hv

good thing is, the value is on the formula sheet so we don't have to memorize it :)

Posted: **Sun Oct 15, 2017 9:11 pm**

when using the equations E=hν and λ=h/p

Posted: **Sun Oct 15, 2017 9:16 pm**

It can also be used to find E (Energy) when the frequency is not known. To do this, you would use the relation v has with c (speed of light) and λ (wavelength).

This results in the equation: E = (hv)/λ

The constant is also used in the uncertainty principle.

Max Planck received a Nobel Prize in 1981 "in recognition of the services he rendered to the advancement of Physics by his discovery of energy quanta".

This results in the equation: E = (hv)/λ

The constant is also used in the uncertainty principle.

Max Planck received a Nobel Prize in 1981 "in recognition of the services he rendered to the advancement of Physics by his discovery of energy quanta".

Posted: **Sun Oct 15, 2017 11:58 pm**

Plank's constant is used in a variety of common equations such as E = (hv)/λ and λ=h/p and it was a constant that was found experimentally.

Posted: **Mon Oct 16, 2017 11:12 pm**

Whenever you see "h" in a formula! Don't get it confused with "p"!!

Posted: **Tue Oct 17, 2017 2:45 pm**

Planck's constant is a set number for the constant h. It is used in formulas, such as E = hv. It will be given to you on the formula sheet. Just to reiterate the above reply, don't get it confused with p. p stands for momentum and is equal to the mass * velocity.

Posted: **Tue Oct 17, 2017 8:59 pm**

Use planck's constant whenever you need to use/derive equations involving the variable h

Posted: **Fri Oct 20, 2017 1:57 am**

Also, make sure the variable is h and not "h bar" (the h with a cross on the top), because h bar refers to the uncertainty principle and has a different value than h, which is Planck's constant.

Posted: **Sat Oct 21, 2017 12:39 am**

Don't forget that the units for Planck's Constant are joules times seconds!

Posted: **Sun Oct 22, 2017 6:52 pm**

You also use Planck's constant in the equation relating the kinetic energy of an ejected e- to the energy of an incident photon.