Electricity

Electric Charge & Current

Electromotive Force & Internal Resistance

Series and Parallel circuits

Series circuit

Parallel circuit

Relationship between Electric Current & Potential Difference

Electric field

Electric current

Electric charge

Different charge-attract

A region around a charged particle or object within which a force would be exerted on other charged particles or objects

I = Q/t

Source of electrical force

Electrial force between two charges-Electrostastic force

Same charge-repel

One electron carry charge of 1.6 X 10^-19 C (coulombs)

Q = ne (n= number of electron) (e=the charge of one electron)

Rate of electic charge flow through a cross section of a conductor

Scalar quantity

Gravitational Potential

Electric Potential

Potential Difference

Ohm's Law

Difference in the amount of energy that charge carriers have between two points in a circuit

Work done per unit mass to move a point from infinity to another point

Electric Potential-Work required to move charge in electric field

Work done that required to move one coulumn of charge between two points

V=W/Q

1V=1JC^-1

V=-GM/r

Work done by moving a charge particle from infinity to another point is equal to the electric potential

Potential difference across an ohmic conductor is directly proportional to the electric current

V ∝ I

V=IR

Resistance

ratio of potential difference to the electric current.

Unit is ohm,Ω

Factors effect resistance

The longer the length of a conductor, the bigger is the resistance

The bigger the cross-sectional area of a conductor, the smaller is the resistance

Type of materials

Resistance of a metallic conductor increases with increasing temperature

image

Electric current passes through two or more branches or connected parts at the same time before it combines again

Has more than one resistor, but only one path through which the electricity flows

I=I1=I2=I3

V=V1+V2+V3

R=R1+R2+R3

I=I1+I2+I3

image

V=V1=V2=V3

1/R=1/R1+1/R2+1/R3

Electromotive Force

The work done by a source in driving a unit charge around a complete circuit.

Formula

ε=V+Ir

Internal Resistance

Resistance present inside a cell, which is against the moving charge due to electrolyte in the cell

Unit: Volt, V

Letter ‘ε’ represent e.m.f

e.m.f is not a kind of force

ε=I(R+r)

The presence of internal resistance causes a voltage drop when a current flows

Electrical Power & Energy

Electrical Energy

Electrical Power

E= VQ

E= VIt

Energy derived from electric potential energy or kinetic energy

Rate, per unit time, at which electrical energy is transferred by an electric circuit

E=Pt

P=VI

P=I^2R

P=V^2/R

Efficiency

(Output energy / Input energy) X 100%

(Output power / Input power) X 100%