# Shared Flashcard Set

## Details

OCR PHYSICS A FORCES FIELDS EN
CAPACITORS
7
Physics
05/27/2008

Term
 what is the meaning of capacitance, and what is its units?
Definition
 the capacitance of a capacitor is the charge stored per unit of potentional difference across it.C = Q / Vthe units a re farads,1F = 1CV-1
Term
 what is the equation to calculate the energy stored on a capacitor?
Definition
 W = 1/2 C V2the unit is joules J
Term
 1. what is the equation for capacitors in parallel? and how whould you calculate the charge?2. what is the equation for capacitors in series?
Definition
 1. Ctotal= C1 + C2Q = Ctotal x V2.            1 = 1 + 1             Ctotal   C1    C2
Term
 what are the three quantities that change as a capacitor discahrges?
Definition
 1. The chage stored, Q.2. the current flowing, I.3. the p.d across the capacitor, V.
Term
 what does the gradient and the area under a charge time graph represent?
Definition
 the gradient- represents the currentthe area under teh graph- represents the charge that has flowed from the capacitor.
Term
 what are the discharge equations?
Definition
 1. Q=Q0e-t/CR2. I = I0e-t/CR3. V = V0e-t/CR
Term
 what is the time constant τ?
Definition
 the quatity CR is called the time constant and its unit is seconds. for a R-C circuit (one in which a capacitor discharges through a resistor)
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