## Planck's Constant

$c=\lambda v$

Husnia Safi - 1K
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Joined: Fri Sep 29, 2017 7:04 am

### Planck's Constant

When would I need to use Planck's constant?

Andrea Grigsby 1I
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Joined: Fri Sep 29, 2017 7:03 am

### Re: Planck's Constant

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 :)

Ruohan Sun 3I
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### Re: Planck's Constant

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

Gurpreet Khamba 1J
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### Re: Planck's Constant

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".

Michelle Lu 1F
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### Re: Planck's Constant

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.

Susie Lee 2I
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### Re: Planck's Constant

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

Posts: 88
Joined: Fri Sep 29, 2017 7:03 am

### Re: Planck's Constant

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.

Josh Moy 1H
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### Re: Planck's Constant

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

Jasmin Tran 1J
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### Re: Planck's Constant

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.

Patricia Macalalag 2E
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### Re: Planck's Constant

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

Christy Zhao 1H
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Joined: Fri Sep 29, 2017 7:07 am

### Re: Planck's Constant

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