P3 Flashcards
how does static electricity work
the electrons are transferred from one object to another to create a static field and even make sparks or shocks
do similar charges repel or attract
repel
do opposite charges repel or attract
attract
what is the force known as between the objects if they repel
electrostatic repulsion
what is the force known as between the objects if they attract
electrostatic attraction
can the current in a circuit flow in an open circuit
no
what is the electric current
it is the rate of flow of electrical charge
what is the value in a single closed loop
the value is the same everywhere
what is potential difference (voltage)
it is the driving force that pushes the charge around
what is resistance
it is anything that resisters the flow of charge
how do you work out the charge of a circuit
current (A) X time (s)
how do you work out the p.d.
current (A) X resistance
what is V = IR
ohms law
what is a linear component
when it has Constance resistance
what is a non-linear component
their resistance changes depending on the size of the current flowing through them
does a current flow through a diode in one or more directions
one direction
how to work out the p.d. in a circuit
work done/charge
how to work out energy transferred in a circuit
charge X p.d.
how to work out power in a circuit
energy (J) / time (s)
how to work out power using the p.d.
p.d. (V) X current (A)
how to work out power using resistance
current2 (A2) nX resistance (R)
how to find p.d. in a parallel circuit
V1 = V2 = V3
how to find the current in a parallel circuit
I = I1 + I2
what is a permanent magnet
it is a magnet that can’t be turned on or off it is just always on
what is an induced magnet
it is a magnet that can be turned on or off
how to make an induced magnet turn on
you can turn on an induced magnet when you put it in a magnetic field
what is a solenoid
it is a coil of wire
how do you increase the strength of a solenoid
by increasing the current or more coils of wire
what is THE RIGHT HAND RULE
using your right hand, point you thumb in the direction of the current and curl your fingers. the direction your fingers are pointing is the direction of the field
what does FLEMING’S LEFT-HAND RULE show
it is used to find the direction of the force on a current-carrying conductor that is at right-angles to a magnetic field
how to calculate the force
magnetic flux density X current X length of conductor
examples of uses of electric motors
factories, electric vehicles and household appliances
what is electromagnetic induction
it’s the induction of a p.d. across a conductor which is experiencing a change in magnetic field
what current do dynamos create
a direct current
what current do alternators create
an alternating current
what are oscilloscopes used for
to see p.d. generated in the coil that changes over time
what is a step-up transformer and how
it takes low volts and turns it into high volts. it starts with low amount of coils to take in the low voltage and gets flipped over to the other side with more coils on the iron core and this turns it into a high voltage to reduce loss of energy when transported across the country
what is a step-down transformer
it takes high volts and turns it into low volts. it starts with high amount of coils to take in the high voltage and gets flipped over to the other side with less coils on the iron core and this turns it into a low voltage to make safer use across the country in homes
calculations for transformers
p.d. across primary coil/p.d. across secondary coil = number of turns on primary coil/number of turns on secondary coil
calculation of transformers
p.d. across primary coil X current in primary coil = p.d. across secondary coil X current in secondary coil
true or false thew attraction of two charged objects is a non contact force
true
name the particles whose movement can cause static charge to build up
electrons
describe how the strength of the electric field of a charged object varies with the distance from the object
as the distance increases from the charged object increases the strength of its electric field decreases
describe the force between two charged objects changes as you move them further apart
the force become smaller
what is is meant by current
the rate of flow of electric charge
true or false current will only flow through an electrical component in a circuit if there is a source of potential difference in the circuit and the circuit is closed
true
