Ohm’s law is written as:I ∝ VV = IR( Where , I = Current, V = Potential DifferenceR = Resistance)
Factors on which the Resistance depends
(i) Directly proportional to the length of conductor(ii) Inversely proportional to the area of cross-section(iii) Directly proportional to the temperature(iv) Depends on nature of the material
Important Electrical Devices
Ammeter: A device to measure current in a circuitVoltmeter: A device which measures the potential differenceRheostat: A variable resistor used to regulate currentElectric Fuse: Protects appliances from short circuit or overloading
Resistances in series
Two or more resistances are connected end to endRs = Rl + R2 + R3 + ........
Resistances in parallel
Two or more resistances connected across the sametwo points
Joule’s law of heating
Heat produced in a conductor is-(i) directly proportional to the square of the current I(ii) directly proportional to resistance R and(iii) directly proportional to the time t
Electric Power
The rate of consumption of electric energy or the rate of doing electric work
Commercial Unit of Electrical Energy: Kilowatt hour(KWh)
The electrical energy consumed by an appliance of 1000 watts in one hour is called 1 kilowatt hour.