Chapter 6: Electricity Flashcards
What are the two main properties of matter?
mass and charge
What is the charge of an individual particle?
1.6 x 10^-19 C (coulomb)
Can you interact with other particles if you have charge?
yes, a charged particle can interact with other particles via a magnetic field
What is current?
The rate of flow of charge
the rate that charge is displaced from one place to another
What is the formula for current ?
I=Q/t
What is the direction of the movement of charge?
from negative to positive
What is the direction of conventional current?
from positive to negative
(opposite to actual charge flow)
(it describes the way a positive charge carrier would travel)
What is potential difference?
the p.d between two points is the work done (energy transferred) in moving a unit charge
to make charge flow in a circuit, energy needs to be transferred to charge (this energy supplied by power supply)
What is the formula for potential difference?
V=W/Q
W=work done
How is resistance created in a circuit?
when electrons collide with atoms and lose energy
What is internal resistance?
it is the resistance created INSIDE the power source when electrons collide with atoms inside the power source and lose energy
What is load resistance?
it is the TOTAL resistance of all the components in the external circuit
otherwise known as ‘external resistance’
What is e.m.f?
electromotive force
it is the amount of electrical energy the battery produces AND transfers to each coulomb of charge
What is the formula for e.m.f?
ε = Energy/Charge
e.m.f is measured in Volts
What is the potential difference across the load resistance?
it is called TERMINAL potential difference (V)
it is the energy transferred when one C of charge passes through the load resistance
If there was no internal resistance, what would terminal p.d equal to?
the terminal p.d would be the same as the electromotive force
What are lost volts?
it is the ENERGY wasted per coulomb overcoming the internal resistance
its symbol is: v
How is a current formed?
by putting a potential difference across an electrical component, then a current will flow
What is resistance?
a measure of how difficult it is for current to flow, it is measured in ohms (Ω)
opposition that a substance offers to a flow of charge
How can you describe resistance at a particle level?
resistance is the result of inelastic collisions between charge carriers and other electrons or ion/atoms in material
inelastic collision=transfers energy to surroundings during collision
What is the formula for resistance?
R=V/I
What is Ohm’s law and what is an ohmic conductor?
Ohm’s law: as long as the physical conditions stay the same, the current through an ohmic conductor is directly proportional to the p.d across it
an ohmic conductor: a conductor that follows ohm’s law
What is a physical factor that resistance is dependent on?
temperature
a higher temp. means that atoms will vibrate more and the electrons (charge carriers) will be scattered more and more inelastic collisions, so more energy lost
What is the resistivity of a material?
it is how difficult it is for current to flow through a material