PHY- 12. current and voltage in circuits

current

the movement of charged particles, the amount of charge passing in one second

coulumb (c)

measure of charge

1 coulumb = 1.6 ×10¹⁹

charge vs current

charge is stationary while current is about movem

current equation

current = charge/ time

I = Q/t

conductor

a material that easily allows electrical charge to flow through them

battery

collection of cells

potential difference (voltage)

the amount of energy given to the electrical charge in a circuit

what is a convectional current

the idea we label current backwards from positive to negative when it actually flows from neg to positive

unit of current

Amps

unit of voltage

volts

what is voltage

the energy of the charges in a circuit

voltage equation

voltage = energy ( joules)/ charge(coulombs)

V = E/Q

open switch

breaks the circuit so current can’t flow

closed switch

completes the circuit so current can flow

cell

provides potential difference

battery

a collection of cells

diode

allows current to flow in one direction

ohmic/ fixed resistor

increases resistance in circuits

variable resistor

can vary potential difference of a circuit by varying resistance

bulb/ lamp

produces light

fuse

if current is too high the fuse melts breaking the circuit and preventing current from flowing

voltmeter

measures voltage

ammeter

measures current

thermistar

as the temperature decreases the resistance decreases

L.D.R

As light intensity increases the resistance decreases

what happens to current in a single circuit vs parallel

current is the same anywhere in a single circuit

in a parallel circuit current is split among the components

what happens to voltage in a single circuit vs parallel

Voltage is split between components in a single circuits

Voltage is the same in each branch of the circuit

where do you place a voltmeter

it only gives hugs around the component

advantages/ disadvantages of a single circuit

• all the components can be controlled by a single switch

• fewer wires are needed

• if one component breaks the whol circuit breaks

• the more components the less voltage each will have

advantages/ disadvantages of a parallel circuit

• if a component breaks the others can still work, important in e.g house lights

• all components in separate loops can be controlled by separate switches

• each loop recieves the same voltage, so you can add more components in separate loops

• sometimes you don’t want each component to have the same voltage, harder to control

• more wires are needed and circuits are more complicated