2014_01_24_Capacitors_1_(Sawtelle)

As the plates get close c it should stay the same

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Unformatted text preview: s a capacitor? •  A way to store electrical energy as a separa0on of charge •  Capacitance: How would we store more energy on our capacitor? Put more charge on the two plates! •  How much charge can we put on a par0cular plate? - + - + - + - + - + 16 Energy ⇒ ΔV Capacitor Equations ΔV = Ed and E = 4π kσ Warning! This “E” is electric field! Q Q σ= ⇒ E = 4π k A A "A% "A% Q =$ 'E ⇒ Q = $ ' ΔV # 4π k & # 4π kd & Q = CΔV What does this “Q” stand for? 4πkc is often written as “1/ε0” 17 What was capacitance again? Qstored C= ΔV !A$ !A$ Q =# & ΔV & ΔV = # " 4π kd % " ε0 d % We lumped this together and called it Capacitance 18 A C= ε0 d What happens to the capacitance as the plates get bigger? A.  It should increase. B.  It should decrease. C.  It should stay the same. + + + + + + + V0 E – – – – – – – 0 19 A C= ε0 d What happens to the capacitance as the plates get bigger? A.  It should increase. B.  It should decrease. As the plates get bigger C.  It should stay the same. we can fit more charge on them! ates. onto t 32 Discuss It! Physicists like to say that a capacitor with a dielectric in between is a good model for a cell membrane. Is this a reasonable star0ng place? 33...
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This document was uploaded on 04/06/2014.

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