PHYSICS DEFINITION:
Potential Difference: Potential difference, V,
between 2 points, A and B, is the energy transferred per unit charge as it
moves from point A to point B.
EMF: Energy transferred per unit charge in driving
charge around a complete circuit.
Electrical Resistance: Ratio of potential difference
to current. Unit – Ohm.
PHYSICS KEYWORD LIST:
Charge carrier: A charged particle that contributes
to an electric current; these may be electrons, protons, or ions.
Quantised: Quantity is said to be quantised when it
has a definite minimum magnitude and always comes in multiples of that
magnitude.
Current: Rate of flow of electric charge past a
point.
Ampere: SI unit of electric current. (abbreviated to
A)
Coulomb: 1C is the charge that flows past a point in
a circuit in a time of 1s when the current is 1A.
Elementary Charge: Elementary charge, e = 1.6 x
10^-19 C.
Number Density: Number of charge carriers, such as
free electrons, per unit volume in a material.
Mean Drift Velocity: Average speed of a collection of
charged particles when there is a current in a conductor.
Homogenous: For an equation to be valid the units
must be homogenous, which means that units, when reduced to the base units, are
the same for each term in the equation.
Ohm: Ohm is the resistance of a component when a
potential difference of 1V drives a current of 1A through it.
PHYSICS CHAPTER WISE SUMMARY:
Electric current is the rate of flow of charge. In a metal,
the charge is electrons; in an electrolyte, it is both positive and negative
ions.
The direction of conventional current is from positive to
negative; because electrons are negative, they move in the opposite direction.
The SI unit of charge is the coulomb (C). 1C is the charge
passing a point when there is a current of 1A at that point for 1s: Charge =
Current x time. (Q = It).
The current I in a conductor of cross-sectional area A
depends on the mean drift velocity (v) of the charge carriers and the number
density (n): I = nAvQ.
Potential difference is used when a charge transfers energy to the component or its surroundings. It is defined as energy
transferred per unit charge: W = VQ.
The term electromotive force describes the
maximum energy per unit charge that a source can provide: W = EQ.
A volt is a joule per coulomb (1 J/C).
Power is the energy transferred per unit of time. P = VI = R(I^2)
= (V^2)/R.
Resistance is the ratio of voltage to current: R = V/I.
The resistance of a component is 1 ohm when the voltage of 1V
produces a current of 1A.
The energy transferred in the circuit over time is given by the equation PV = W/Q, W = VQ, or W = IVt.
PHYSICS IMPORTANT NOTES:
Charge = Current x time (Q=It)
I = nAvQ
Energy transferred = potential difference x charge (W = VQ)
Resistance = Potential difference/current (V = IR)
P = VI = R(I^2) = (V^2)/R
|
Quantity |
Symbol of
quantity |
Unit |
Symbol of
Unit |
|
Current |
I |
Ampere |
A |
|
Voltage (p.d,
e.m.f) |
V |
Volt |
V |
|
Resistance |
R |
Ohm |
Ω |
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