Physics-electrcity Flashcards
What is the basic concept of electricity?
Static electricity is electric charges basically gong nowhere. Electric current is a net flow of electric charge.
What is the units of electric charge?
Electric charge is in coulomb, C
What is electric current measured in?
Measured in Coulombs per second, aka Amperes
What is the electric current equation?
i=q/t Where i is the current in Amperes Q is the total amount of charge (in coulombs) t is time in seconds
Conductors vs Insulators:
In a conductor, electric current can flow freely, in insulators it cannot.
Write the variations of the electric current equation:
i=q/t.
t=q/i
q=it
Write how to change milli, micro and nano:
Milli= x10^-3 Micro= x10^-6 nano= x10^-9
Why do electrons come out of the negative terminal?
Electrons have a negative charge and therefore are attracted to the positive terminal.
Write Ohm’s law:
V=IR
Explain resistance:
Resistance is a property of a component that describes its tendency to oppose the flow of electric current. Good conductors have very low resistance.
Explain voltage:
Potential difference is measured from on point in the circuit to another point. Voltage does NOT go through things.
Explain Current:
Current is measured at a point. Current DOES flow through things.
Write the variations of ohms law:
i=V/R
R=V/I
What is the two ways resistors can be combined?
Circuit elements can be connected in two ways:
SERIES (one after the other)
PARALLEL (met at the same time by the current)
Fact about series:
Connecting resistors in series always increases the total resistance.
Fact about parallel:
Connecting resistors in parallel always decreases the total resistance.
Series resistance formula:
Req=R1+R2+R3…..
Parallel resistance formula:
1/Req=1/R1+1/R2+1/R3….
Warning for parallel resistors:
The formula for resistors in parallel does not give the answer, but rather the recipricol of the answer.
Basic formula for electric power:
P=V.i
Rewrite the electric power formula using ohm’s law:
P=V.i
P=i^2.R
P=V^2/R
Write the formula for the rate of doing work (power):
P=w/t
where P=power (in watts or joules/second)
w=work (in joules)
t is time (in seconds)
Formula for energy:
Energy=powere x time
Insulators:
Most solid materials are classified as insulators because they offer very large resistance to their flow of electric current.
Conductors:
Metals are classified as conductors because their outer electrons are not tightly bound.
