Grade 9 Electricity (current) Flashcards
What is Current
The amount of charges (electrons) that flow past a point in a circuit within a specific time
How do we measure charge?
A standardised number of electrons are used to represent one charge; a Coulomb (C)
1 Coulomb =
6.24 x 10^-18 electrons
How do we measure current?
Using an ammeter we can measure how many Coulombs pass through a wire per a second
“I” represents…
Current (measured in Amperes [A])
“Q” represents…
Charge (measured in Coulombs [C])
“t” represents
Time (measured in seconds [s])
Formula for Current
Charge/time
Formula for Charge
time x current
Formula for time
Charge/current
2 characteristics of direct current (D.C.)
- charges move in one direction (neg - pos)
- produced by batteries
2 characteristics of alternating current (A.C.)
- charges move in both directions (back and forth)
- produced by generators; used in homes
What does EPE stand for?
Electrical Potential Energy
What is Electrical Potential Energy?
The energy stored in a group of electrons. The more energy the electrons have, the more electrical potential they have
Why is it safe to touch both terminals of a AA battery but unsafe to touch both terminals of a wall outlet?
the AA battery has less EPE than the wall outlet
How can we measure EPE?
In circuits we don’t measure the total energy. We measure the difference in the energy the electrons have as they travel across a source or a load
Define Voltage
Voltage is the difference in EPE between two points in a circuit
