Electricity Flashcards
State Ohm’s Law.
A:
Ohm’s Law states that the p.d. across a metallic conductor is proportional to the current through it, provided the physical conditions do not change.
Resistivity:
what is the effect of increasing temperature on the resistance of metal conductors?
A:
Resistance increases
Resistivity:
What is each variable for the equation:
ρ = RA/L
A:
ρ = resistivity R = resistance A = cross sectional area L = length of the wire
Resistivity:
explain the term Superconductor.
A:
A superconductor is a wire or a device made of material that has zero resistivity at and below a critical temperature.
this property is known as superconductivity.
Resistors:
How do you calculate the total resistance of resistors in series?
A:
RT = R1 + R2 + R3 + …
Resistors:
How do you calculate the total resistance of resistors in parallel?
A:
1/Rt = 1/R1 + 1/R2 + 1/R3 +…
Circuits:
E = I x V x ?
A:
E = IVt
Potential Divider:
What is a potential divider used for?
A:
Used to supply constant or variable p.d. from a power supply.
(spec ref: 3.5.1.5)
Current Rules:
At any junction in a circuit, the total current leaving the junction is _______ to the current entering the junction.
A:
EQUAL
Current Rules:
Components in series:
the current entering a component is___ ______ as the current leaving the component.
A:
the same
P.d. Rules:
for two or more components in series , the total pd across all the components is…
A:
…equal to the sum of the potential differences across each component.
Terminal pd:
the terminal pd is also known as?
A:
e.m.f.
Resistance:
the rate of heat transfer = ?
A:
I^2 x R x t
emf & internal resistance:
define the internal resistance of a source.
A:
the resistance of a source is the loss of potential difference per unit current in the source when current passes through the source.
emf & internal resistance:
define the electromotive force.
A:
the electromotive force of the source is the electrical energy per unit charge produced by the source.
