Positive and Negative signs?

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MKearney_4G
Posts: 50
Joined: Fri Aug 30, 2019 12:18 am

Positive and Negative signs?

Postby MKearney_4G » Mon Oct 14, 2019 5:28 pm

I am unclear as to why sometimes we say that the energy is negative and sometimes it is positive. Could somebody explain what the signs mean in the context of Energy?

Christineg1G
Posts: 115
Joined: Fri Aug 09, 2019 12:15 am
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Re: Positive and Negative signs?

Postby Christineg1G » Mon Oct 14, 2019 5:36 pm

I believe that if energy is leaving a system or if the force and displacement are moving in the opposite direction, then we use a negative sign to represent that. And vice versa if energy is entering a system, or the force and displacement are moving in the same direction, we would use a positive sign.
Hope this helps!

KDang_1D
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Re: Positive and Negative signs?

Postby KDang_1D » Mon Oct 14, 2019 6:02 pm

Positive energy is an increase in the system (coming in), and negative energy is a decrease in the system (going out)

E=hv is positive because you're simply analyzing energy that is already there. E=(-hR)/n^2 is negative because the electron's energy is being emitted as a photon.

Khushboo_3D
Posts: 60
Joined: Wed Sep 18, 2019 12:19 am

Re: Positive and Negative signs?

Postby Khushboo_3D » Mon Oct 14, 2019 6:43 pm

You would have a negative sign when energy is emitted- electron moves from. higher to lower energy level- and a positive sign when energy is absorbed- electron moves from lower to higher energy level.

xenamclean_1G
Posts: 51
Joined: Sat Jul 20, 2019 12:15 am

Re: Positive and Negative signs?

Postby xenamclean_1G » Mon Oct 14, 2019 6:46 pm

A negative sign in front of energy would indicate an emission of energy (the electron moves from a higher to a lower energy level. Positive is just the vice-versa of this (a lower to a higher energy level).

Osvaldo SanchezF -1H
Posts: 122
Joined: Wed Sep 18, 2019 12:21 am

Re: Positive and Negative signs?

Postby Osvaldo SanchezF -1H » Mon Oct 14, 2019 6:56 pm

The positive and negative signs are just indicative of direction in which the energy is coming from, whether it is emitting into or out the system. It is like a vector which shows the direction in which the energy is going too.


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