Can someone explain the equation for entropy?

Here's the equation:


$\Delta S = \frac{\Delta q}{T}$


The confusion I have with this equation lies in the variable for temperature, $T$. Why is the temperature constant in this equation? Why can't the equation include $\Delta T$ instead of just $T$ and, surely, if $\Delta q$ is negative or positive the temperature must decrease or increase, respectively.




Your relation is not correct, so you must not understand something. If I were you I will asked the question in Physics SE but nevermind. 


The good relation is : $$\mathrm{d}S=\frac{\delta Q}{T}$$ 


I let Richard Feynman explain it to you [here](http://www.feynmanlectures.caltech.edu/I_44.html#Ch44-S6) (when you click on the link wait few seconds)


I hope it will help you, have fun, live long and do chemistry ! 


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