Physics - Circuits Test

Circuit Requiments

• a power soure to move charges through the circuit. this serves as an electron pump, supplying energy, not electrons.

• Circuit needs complete conductive loop from the negative terminal to the positive terminal of the power source

• a resistive load in the circuit that uses the enrgy from the electrons

circuit diagram sysmols - power source

supplies energy to the electrons —-| │—

circuit diagram symbols wires

conductive connections ——-

circuit diagram symbols - switch

connect/disconnet wires

circuit diagram sysmobls - resistors

use the energy in the circuits

circuit diagram symbols - bulb

uses up energy and converts to light and heat

circuit diagram symbols - voltmeter

measures voltage drops and gains

circuit diagram symbols - ammeter

measures current flow

current

flow of electrons

current path

a path that an electron could take starting from the power source going out through the circuit and back to the other side of the power source

series

two objects wired in SERIES are on the same current path

paralell

two objects wired in PARALLEL are on separte current paths

short circuit

a path of NO resistance (just a wire, no bulb) that will draw all the current away from other possible paths

dangerous: the unreisted electrons drastically increase current flow

current def

rate of flow of charge

symbol for current

symbol for current is I

unit for current

unit for current is “Amp” ampere (A)

what is an amp

amp=coulomb worth of electrons passing a point each second (C/s)

Ammeter

measures current flow, wired in series

junction rule (for current)

at any point in a circuit the total incoming and total outgoing current must be equal

voltage drops and gains (Elecrtic potential difference)

is the charge in amount of electric potential energy per coulomb of charge

voltage drop

electrons naturally lose energy where there is resistance

voltage gain

power source does work to increase energy

symbol for voltage

symbol for voltage is V

unit for voltage

unit for voltage is volt (v)

what is a volt

a volt is a joule of energy per coulomb of charge (J/C)

voltmeter

measures voltage drops or gains, wired in paralell

loop rule (for voltage)

going around a complete current path, all the voltage drops must add up to equal the voltage gains

how to calculate power output?

• power tells us how quickly energy is converted out of the circuit (Watt=J/s)

• to calclate the power output for a given reistance: P=IV

power

rate at which a resistor does work converting energy

symbol for power

symbol for power is P

unit for power

unit for power is watt (W)

what is a watt

watt= joule of electric potential energy converted into light, heat, or KE per sec (J/s)

resitance (where voltage drops occur)

the meausre of how much of an insultor something is

symbol for resistance

symbol for resistance is R

unit for resistance

unit for resistance is Ohm (Ω)

what is an ampere equivalent to

an ampere is equivalent to C/s

what is a watt equivalent to

a watt is equivalent to J/s

determining the resistance of an object

width: thin more, thick less. length: long more, short less. temp: hot more, cool less.

Ohm’s Law

V/R=I

using ohms law

ohms law works for both a single resitor AND the whole circuit

the total resistance of a circuit determins how much current is drawn from a power source of a given voltage so, Itotal=Vpower source/Rtotal

VIRP: rule for power (energy conservation)

the power input to the electrons by the power source must equal the total power output of the elctrons at all of the resistances in the circuit

equivalent resistance

replacing two or more resistors with an equivalent resistance does not change the voltage across or current through the power source

helpful equations

I=V/R and P=IV

current symbol and unit

current symbol is I and unit is A

current unit equvalent

current unit equivalent is C/s

current measured with/Equation

current measured with/Equation: ammeter (series), I=V/R, P=IV

current how it works within a circuit

current: rate of flow of charge, junction rule-at any point in the circuit, incomming and outgoing current is equal

voltage (potential difference) symbol and unit

voltage symbol is V and units is V

voltage unit equivalent

voltage unit equivalent is J/C

voltage measured with/Equation

voltage meausred with/Equation: voltmeter (parallel), V=IR, P=IV

how voltage works withing a circuit

voltage: change in electric potential energy per coulomb from one point to another, loop rule-on any current path the voltage drops are equal to the voltage gains

resistance symbol and units

resistnce symbol is R and units is Ohms

resistance unit equivalent

resistance unit equivalent is (V/A)

resistance measured with/Equation

resistance measured with/Equation: R=V/I

how resistance works within a circuit

resistance: measure of how much of an insultor something is, equivalent resistance-replacing 2 or more resistors with one equiavlent resiitor does not change the current through or voltage across the power source.

Req=R1+R2+R… (series)

1/Req= 1/R1+ 1/R2 + 1/R… (parallel)

power symbol and units

power symbol is P and units is W

power unit equivalent

power unit equivalent is J/s

power measured with/Equation

power measured with/equation: P=IV

how power works withng a circuit

power: rate of energy converted, total energy output of resistrors=total energy input by power source (energy conservation)