h vs. ħ?


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Angel More
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h vs. ħ?

Postby Angel More » Thu Oct 29, 2020 7:17 pm

Can you explain the difference between h (6.62607015×10−34) and ħ (h-bar) (1.054571817×10−34) to me please?

And when do we use the 1) formula and the 2) formula?

1) ∆p ∆x ≥ h/4π
2) ∆p ∆x = (1/2) ħ

Thank youuuuu

Alexandra Ahlschlager 1L
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Re: h vs. ħ?

Postby Alexandra Ahlschlager 1L » Thu Oct 29, 2020 7:22 pm

I think the h-bar symbol represents h/2pi, so (½)h-bar would be equal to h/4pi. Since both equations are basically equivalent to each other, I’m pretty sure you can use whichever form you’re most comfortable with. Hope this helps!

Nathan Lao 2I
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Re: h vs. ħ?

Postby Nathan Lao 2I » Thu Oct 29, 2020 7:25 pm

h is Planck's constant, which is defined as 6.626x10^-34 J s. ħ is equivalent to Planck's constant(h)/2pi. I'm assuming the second formula should have a ≥ instead of an = sign but the formulas should represent the same thing, just in different notations.

The textbook also explains this in section 1B.3 The Uncertainty Principle.

AustinMcBrideDis3L
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Re: h vs. ħ?

Postby AustinMcBrideDis3L » Thu Oct 29, 2020 7:42 pm

ħ is just some chemistry technical term/jargon for h/2π. Thus when its (1/2)*ħ it equals the h/4π in the other equation. Also the equations should both have a greater than or equal to sign, so I don't know why there is a discrepancy there.

Charlie Russell 2L
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Re: h vs. ħ?

Postby Charlie Russell 2L » Thu Oct 29, 2020 8:56 pm

ħ is not h/4pi!!! It is h/2pi. 4pi was only in the equation used for the midterm because there was a 2 in the denominator to multiply!

Adrienne Yuh 2B
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Re: h vs. ħ?

Postby Adrienne Yuh 2B » Fri Oct 30, 2020 2:10 pm

The h-bar symbol represents 2pi! I would ultimately just follow the formula sheet to keep it a familiar representation of the equation.

Aayushi Jani 3A
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Re: h vs. ħ?

Postby Aayushi Jani 3A » Fri Oct 30, 2020 8:59 pm

h-bar is h/2pi. You can use either equation, but personally, I prefer just remembering h and using ∆p ∆x ≥ h/4π.

Jaden Haskins 2E
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Re: h vs. ħ?

Postby Jaden Haskins 2E » Sat Oct 31, 2020 2:19 pm

Is h-bar used in any other circumstances, or is the indeterminacy equation the only one that uses this?

Olivia Monroy 1A
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Re: h vs. ħ?

Postby Olivia Monroy 1A » Sat Oct 31, 2020 2:35 pm

I prefer using the equation with just h, as that's what Lavelle teaches, but the textbook uses the other just to symbolize h/2pi.. they're the same thing/interchangeable.

Bella Bursulaya 3G
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Re: h vs. ħ?

Postby Bella Bursulaya 3G » Sat Oct 31, 2020 2:41 pm

Hi! h is planck's constant, and h bar is a reduced value of h. 1/2h/2pi is the same thing as h/4pi, they equal the same value. The equations should both have a greater than or equal sign, but equal is the most optimistic value. I hope this helps!

t_rasul2I
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Re: h vs. ħ?

Postby t_rasul2I » Sun Nov 01, 2020 8:19 pm

I understand that h bar is the same set up as h/4pi. But why do we have a complicated/different set up of the equation. Is there something it was derived from?

Griffin G
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Re: h vs. ħ?

Postby Griffin G » Sun Nov 01, 2020 11:28 pm

ħ, or h bar is simply h/2pi. h as you know is plancks constant. h bar exists just to save space. So (1/2)ħ is the same as h/4pi.


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