Physics: Lesson 2 (Current and Voltage)

_____ can be moved between objects (which subatomic particle)

electrons

______ remain on the object unless they’re discharged to another object or until they build up enough energy to jump (sparks)

electrons

current electricity

in current electricity, the electrons constantly flow along a conductor

conductor

a material that allows heat and electricity to flow through it

insulator

a material that does not allow heat and electricity to flow through it

current (I)

movement of electron flow, measured in Amperes (A)

measure of how many electrons pass a point each second (not the speed of electrons)

more _____ = more ______

electrons, current

how to calculate current?

I = current (in Amp)

Q = amount of charge (in Coulombs, C)

T = time (in seconds, s)

I = Q_

     t 

electrical energy provides what with energy?

devices. for example, lightbulbs, TVs, etc.)

electrons carry that energy through the circuit, and when they reach a device, energy is given to the device

loss in energy is called?

potential difference (voltage)

like a push of the electrons

find voltage by looking at the ______

difference between the energy carried by the electrons before and after the device

the greater the voltage, the greater the ____, which usually means a greater ______

push, current

a potential difference also occurs at a device that provides the energy (like _____)

a battery

the energy provided by the battery is given to all the electrons at once (not just those near or inside the battery)

potential difference: ____ from the battery

push

electrical energy calculations (formula)

calculate voltage using this formula: v = e/q

v = potential energy/voltage (in volts, V)

e = energy (joules, J)

Q = amount of charge (in Coulombs, C)

e

v q

current and voltage: why do we need different current and voltages?

phone: a phone uses very little energy, so it needs a lower voltage

• current has a consequence of heating wires up. thinner wires get hot quickly and can melt

• in a phone wires are very think so a low current is needed

small appliance (iron)

• iron needs a lot of energy (therefore needs a higher voltage)

• we want iron to get hot and so a high current is needed

• also has a thicker wire