Physics Quicksheets - DC and AC Circuits

Current: the flow of electric charge.  Current is given by:

 

SI units: Amp (A) = C/s

*The direction of current is the direction positive charge would flow, or from high to low potential.

V = IR 

*can be applied to entire circuit or individual resistors.

Opposition to the flow of charge.



*Resistance increases with increasing temperatures with most conductors)

SI units: Ohm (Ω) = 

1. At any junction within a circuit, the sum of current flowing into that point must equal the current leaving.

2. The sum of voltage sources equals the sum of voltage drops around a closed circuit loop.

• I = Constant 
• R_eff = R₁ + R₂ + R₃ +...
• V_eff = V₁ + V₂ + V₃ + ...

• V = Constant
• 

I_eff = I₁ + I₂ + I₃ + ...

SI units: Watt (W) = J/s

the ability to store charge per unit voltage.

It is given by:   or  

ε₀ = 8.85 x 10^-12 C²/N*m²

SI units: Farad (F) = 

nonconducting material that increases capacitance.

C_new = kC_old

K = constant dependent on material