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urp:physelec
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urp:physelec [2021-11-06] nerf_herder created |
urp:physelec [2021-11-06] nerf_herder |
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| ====Circuits==== | ====Circuits==== | ||
| - | Power = watts, current (I) = amps, volts (E or V) | + | Power = watts, current (I) = amps, volts (E or V), resistance (R) = ohms |
| * **Ohm's Law** e = ir | * **Ohm's Law** e = ir | ||
| - | * p = ie | + | * p = ie = i²r |
| - | * p = i²r | + | |
| - | Resistors in series add together | + | Resistors in series add together |
| - | Resistors in parallel: 1/Rt = 1/R₁ + 1/R₂ + ... | + | |
| - | current in parallel: if have V, compute R for each path | + | Resistors in parallel: 1/Rt = 1/R₁ + 1/R₂ + ... |
| - | For two paths, R₁ & R₂: I on R₁ = R₁/(R₁+R₂) | + | |
| + | current in parallel: if have V, compute R for each path. For two paths, R₁ & R₂: I on R₁ = R₁/(R₁+R₂) | ||
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| - | Voltage divider: (R₂ is resistor between Vout and ground) | + | Voltage divider: Vout = R₂/(R₁+R₂) * Vtotal, where R₂ is resistor between Vout and ground |
| - | Vout = R₂/(R₁+R₂) * Vtotal | + | |
| + | Joules = watts * seconds | ||
| ====capacitance==== | ====capacitance==== | ||
| - | Q = CV , Q = charge (coulombs, always a positive value), | + | Q = CV , Q = charge (coulombs, always a positive value), C = capacitance (farads), V = voltage |
| - | C = capacitance (farads), V = voltage | + | |
| parallel plate capacitor | parallel plate capacitor | ||
| - | C = epsilon (A/d), A = area, d = distance between plates | + | C = epsilon (A/d), A = area, d = distance between plates |
| epsilon = permittivity of the dielectric | epsilon = permittivity of the dielectric | ||
| dielectric constant (over free space) = 8.84 * 10⁻¹² Farads/meter | dielectric constant (over free space) = 8.84 * 10⁻¹² Farads/meter | ||
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| sigma = Q/A | sigma = Q/A | ||
| - | Force between two charged objects: Use coulomb's law: | + | **Coulomb's law**: Find force between two charged objects |
| - | F = k * q1 * q2 / r² | + | F = k * q₁ * q₂ / r² |
| k = 9 * 10⁹ N m²/C² | k = 9 * 10⁹ N m²/C² | ||
| r = distance in meters | r = distance in meters | ||
| C = coulombs | C = coulombs | ||
| + | C = Q/V = Q/Ed = A*epsilon/d | ||
| ====Point Charges==== | ====Point Charges==== | ||
| + | Back to [[Physics]] page or [[00_start|Start]] page. | ||
urp/physelec.txt · Last modified: 2021-11-06 by nerf_herder
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