P4 Flashcards
IF AN ATOM HAS NO CHARGE…
It has equal numbers of protons and electrons
IF AN ATOM HAS A POSITIVE CHARGE…
Loss of electrons more protons then electrons
IF ATOM HAS A NEGATIVE CHARGE….
Gain of electrons more electrons than protons
WHAT IS STATIC ELECTRICITY?
Build up of charge on insulating materials
HOW DOES STATIC ELECTRICITY HAPPEN?
When you rub two insulating materials together electrons are rubbed off one and passed onto the other
HOW DO WE KNOW WHICH WAY ELECTRONS ARE TRANSFERRED?
We dont it depends on properties of the materials
WHAT WAY DO FIELD LINES GO OUT ON POSITIVE CHARGED?
Outwards
WHAT WAY DO FIELD LINES GO ON NEGATIVE CHARGED?
Inwards
WHAT IS THE THREE RULES FOR OBJECTS WITH FIELD LINES
- They are non contact force so field and force between gets weaker as you get further away
-Opposites attract so positive attracts a negative
-Force inbetween is called electrostatic attraction
WHAT IS CURRENT MEASURED BY?
An ammeter
DEFINE CURRENT?
A measure of flow of electrons
WHICH WAY DOES CURRENT FLOW?
From positive terminal of battery to negative terminal
WHAT IS CURRENT MEASURE IN?
Amperes (A)
WHAT IS THE EQUATION FOR CURRENT?
I= Q / t
Current= charge flow / time
WHAT IS POTENTIAL DIFFERENC MEASURED WITH?
A voltmeter
DEFINE POTENTIAL DIFFERENCE?
Force driving the flow of electrons
( provided by cell or battery )
WHAT IS POTENTIAL DIFFERENCE MEASURED IN?
Volts ( V )
WHAT IS THEEQUATION FOR POTENTIAL DIFFERENCE?
V= I x R
P.D = Current x Resistence
WHAT IS RESISTENCE?
Everything that resists the flow of electrons
WHAT IS RESISTENCE MEASURED IN?
Ohms
WHAT IS THE EQUATION FOR RESISTENCE?
R = I / V
Resistance = Current / P.D
WHAT IS CHARGE?
A measure of total current that flows with in a certain period of time
WHAT IS CHARGE MEASURED IN?
Coulombs ( Q )
WHAT IS THE EQUATION FOR CHARGE FLOW?
Q = I x t
charge flow = Current x time
WHAT IS THE JOB OF A CELL?
pushes electrons around the circuit
WHAT IS THE JOB OF A SWITCH?
Enables current in circuit to be switched on and off
WHAT IS JOB OF FILAMENT LAMP?
emits light when current runs through it
WHAT IS THE JOB OF AN AMMETER?
To measure electrons current
WHAT IS THE JOB OF A VOLTMETER?
to measure potential difference
WHAT IS JOB OF A FIXED RESISTOR
limits current in circuit
WHAT IS JOB OF A VARIABLE RESISTOR?
allows current to be varied
WHAT IS JOB OF A FUSE?
If current gets to high it is designed to melt and break circuit
WHAT IS JOB OF A DIODE?
Only allows current to flow in one direction
WHAT IS JOB OF A LDR?
Changes resistance due to intensity of light
WHAT IS JOB OF THERMISTOR
Limits current in circuit based off temperature
WHAT IS JOB OF A LED?
Emits light when current passes through it one way
HOW MANY LOOPS DOES A SERIES CIRCUIT HAVE?
one loop
IN A SERIES CIRCUIT HOW ARE THE COMPONENTS CONNECTED?
one after another
IN A SERIES CIRCUIT HOW IS CURRENT SHARED?
It is same in every point of the circuit so ammeter can be placed anywhere
IN A SERIES CIRCUIT HOW IS POTENTIAL DIFFERENCE SHARED?
P.D of battery is shared across all components
- IF SAME COMPONENT SAME VOLTAGE
- total= V1+V2+V3
IN A SERIES CIRCUIT HOW DOES RESISTENCE WORK?
Total resistance is sum of resistance of all components
HOW MANY LOOPS DOES A PARALLEL CIRCUIT HAVE?
more than one
IF A LOOP HAS A GREATER RESISTANCE IN PARALLEL…
it will take less share of current
IN A PARALLEL CIRCUIT HOW IS CURRENT SHARED?
Across loops in anyway
HOW IS POTENTIAL DIFFERENCE SHARED IN A PARALLEL CIRCUIT?
every component gets full source of P.D
HOW DOES RESISTENCE WORK IN A PARALLEL CIRCUIT
more components added in parallel resistance lowers
WHY IS CURRENT SHARED ACROSS BRANCES IN A PARALLEL CIRCUIT
because different junctions so different amount of charge can flow through different components
