Topic 9 Flashcards
An electric current is the rate of
Flow of charge
Unit for charge
Coulombs C
One ampere or amp A is one
Coulomb of charge per second
Charge =
Current x time
A x s
When will electric current flow?
In a closed circuit when there is a source of potential difference
Describe how ammeters should be connected with components in circuits
Ammeters should always be arranged in series with the component to be measured
Energy transferred =
Charge moved x potential difference
What does ohms last state
How the current through a component related to its resistance and the potential difference across it
The resistance of a component is a way of measuring how
Hard it is for electricty to flow through it
Unit for resistance
Ohms
Resistance up current
Down
The resistance of a circuit can be changed by putting different
Resistors into the circuit or by using. Sbariable resistor. The resistance of a variable resistor can be changed using a slider of knob
Ohms law states that the size of the current, i, flowing through a component of resistance, r, is
Directly proportional to the potential difference, v, across the component at constant temperatures
Equation for Omhs law
Potential difference = current x resistance
Components that obey ohms law are said to be
Ohmic comduxtors whereas those that do not obey are non-ohmic
For resistors in series:
The current through each resistor is the same value
The sum of the voltages across the resistors must add up to equal the cell voltage
For resistors arrange in parallel
The total curren leaving the battery is equal to the sum of the current flowing incthe speedster branches
The potential difference across the resistors in each branch is equal to the potential difference of the battery
The resistance of a LDR is large in
The dark
The resistance gets less if light shines on it
The resistance of a thermistor depends on its temperature
The high the temperate the
Lower the resistance
When a current flows in a circuit it has a
Heating effect
