Circuits and electrical eqations Flashcards
Q means
Charge (c)
I means
Current (A)
t means
Time (s)
P means
Power (W)
E means
Energy (J)
R means
Resistance (ohms)
Equation linking charge, current and time
charge (c) = current (A) x time (s)
Equation linking power, current and voltage
power = current x voltage
Equation linking power energy and time
power = energy / time
Equation linking energy, current, voltage and time
energy = current x voltage x time
Equation linking voltage current and resistance
voltage = current x resistance
Equation linking energy voltage and charge
energy = voltage x charge
What is AC
Alternating current varies from a posotive to negative maximum. Eg anything you plug into a power socket in your house is recieving AC.
What is DC
Direct current has a fixed value and only goes one way around the circuit. Eg batteries and cells.
What is an earth wire’s job?
- Appliences in a metal case must be earthed
- If the live wire comes loose inside and touches the metal case you could recieve an electric shock
- One end of the earth wire is connected to the metal case
- The earth wire provides a lower resistance route for the current to take; the current flows to the earth, rather than through the user
- As the resistance is low, a high current flows which blows the fuse
