# 3 Energy and Voltage Flashcards

What is the unit for current?

ampere / amps or A

Define current

The rate of flow of charge OR the number of coulombs passing a point in a circuit per unit time (It is not the speed of the electrons!)

Describe what it means when 1 A is passing through a circuit

1 A = 1 Coulomb per second

What is the unit for energy?

joules

How is energy related to current, voltage and time?

E = IVt

What is voltage measured in?

Volts or V

Define voltage

It is the energy per unit charge either supplied by a cell, or transferred to a component.

How does voltage related to current and resistance?

V=IR

What is a volt?

1 V = 1 J/C 1 volt = 1 joule per coulomb

What is resistance?

a measure of how much voltage is needed per amp of current. It is a measure of the is a measure of the tendency of a material to resist the flow of an electrical current.

How is power related to current and voltage?

P=IV

What is power measure in?

Watts (W)

What is a watt?

1 W = 1 J/s I Watt = 1 joule per second

How is voltage related to energy and charge?

V=E/Q

Voltage = Energy / Coulomb

Voltage lost across a component is a measure of the energy lost across the component per coulomb

What is the voltage across a cell or power supply a measure of?

The energy transferred from chemical store to electrical in the wires per coulomb