Electricity Flashcards
(29 cards)
What is the equation for energy transferred?
E = V x Q Energy transferred = Voltage x Charge or E = V x I x t Energy transferred = Voltage x Current x Time
What is the equation for potential difference?
V = W / Q Voltage = Work Done / Charge
What is the unit for charge?
Coulombs
What is the unit for work done?
Joules (J)
What is Ohms Law?
V = I x R
What is the equation for charge?
Q = I x t Charge = Current x Time
What is the rule for CURRENT in a SERIES circuit?
Current is the SAME everywhere in the circuit.
I1 = I2 = I3
What is the rule for VOLTAGE (or P.D.) in a SERIES circuit?
The voltages of all the components ADD UP to the voltage of the battery.
V Battery = V1 + V2 + V3
What is the rule for CURRENT in a PARALLEL circuit?
The current in each branch ADDS UP to form the total current going in and out of the battery.
I Total = I1 + I2 + I3
What is the rule about VOLTAGE (or P.D.) in a PARALLEL circuit?
The voltage of each branch is the SAME as the battery voltage.
V Battery = V1 = V2 = V3
What is the rule about RESISTANCE in a SERIES circuit?
Total resistance is equal to the resistance of all the components ADDED UP.
R T = R1 + R2 + R3
What is the rule about RESISTANCE in a PARALLEL circuit?
1/RT = 1/R1 + 1/R2 + 1/R3
How can you tell if a graph is directly proportional?
The line is straight and goes through the origin.
What does a directly proportional V/I graph tell you about a component?
It is an Ohmic resistor.
What is current?
The flow of charge (electrons).
What is a battery?
Two or more cells connected together.
What does Ohm’s law state?
Current through a resistor at constant temperature is directly proportional to the potential difference across the resistor.
What does the gradient of the line in a V/I graph tell you about the component?
The steeper the line, the greater the resistance.
What is an Ohmic resistor and a Non-Ohmic resistor?
Ohmic
• Straight line through origin (V/I graph)
• Resistance does not change with increased current
Non-Ohmic
• Curved line (V/I graph)
• Resistance changes with increased current
Why does resistance increase with current in Non-Ohmic resistors?
Greater current heats up the wire. This causes the ions in the metal to vibrate more, blocking flow more and therefore increasing resistance. The result is a curved graph.
What are some examples of Non-Ohmic and Ohmic resistors?
Ohmic • Fixed Resistor Non-Ohmic • Filament Bulb • Diode
What does the V/I graph look line for a fixed resistor?
Straight line through the origin.
What does the V/I graph look line for a filament bulb?
It curves away from the current axis as current increases.
What does the V/I graph look line for a diode?
Along the voltage axis until a certain current, then sudden spike up.
