Unit 2: 4 - Current Electricity Flashcards
What happens when 2 electrically insulating objects rub against each other?
Electrons are rubbed off one material and deposited onto the other.
The material which gains electrons becomes _____ charged. What is this called?
Negatively. Charging by friction.
What will happen if 2 negatively/positively charged objects come close to each other?
Repel
How do we work out the current using Coulombs?
I=Q/t
Current = Coulombs / Time
What is the unit of Potential Difference?
Volt
How is Potential Difference worked out using Work Done?
V=W/Q
Voltage (V) = Work done (J) / Charge in Coulombs (Q)
What does Ohm’s Law state?
The current through a resistor at constant temperature is directionally proportional to the potential difference across the resistor.
Reversing the current through a component reverses the _____ _____ across it.
Potential Difference.
How do we work out the resistance?
R=V/I
Resistance (Ohms) = PD (V) / Current (I)
What is an component classified as when it obeys Ohm’s law?
An Ohmic Conductor
In what way does a current flow through a diode?
In one direction, as the resistance is too high.
How does the resistance of a Light Dependant Resistor change with the light intensity?
As the light intensity gets larger, the resistance goes up.
How does the resistance of a thermistor change with temperature?
As the temperature goes up, the resistance of a thermistor goes down.
What is a series circuit?
When components are connected one after another. If there is a break anywhere in the circuit, the charge stops flowing.
How do we work out the current using the resistance?
I=V/R
Current = PD / Resistance
How do we work out the total resistance of a circuit?
The sum of all the resistances of the components in the circuit.
How is a parallel circuit arranged?
Each component is connected across the supply; if there is a break in one part of the curcuit, charge can still flow through the other components.
The sum of the current through the whole circuit is equal to the sum of the currents through the _____ components.
Separate
Define current.
Rate of flow of charge.
What is potential difference?
Work done / energy transferred per coulomb of charge.
