CBSE Electricity Subject Notes
CBSE Guess > eBooks > Class X > Electricity by Mr Sunil D Chauhan
Electricity
Electricity
Characteristics of a fuse wire A fuse wire should have short length, high resistance and low melting point.
- Heating effect is useful in electric iron, electric heater, geyser, toaster, etc.
- The filament of the bulb is made of tungsten because its melting point is very high.
- The inactive gases filled in bulbs are nitrogen and argon.
- The three important effects of electric current are heating effect, magnetic effect and chemical effect.
- 5A fuse wire is used for low power appliances like mixer, bulbs, tubes, fans, etc.
- 15A fuse wire is used for high power appliances like AC, electric heaters, geysers, ovens, etc.
Electric power The electric work done in unit time is called electric power. It is represented by P. Its SI unit is watt (W) which is also known as joule per second.
Electric power = electric work done / time i.e. P = W/t
One watt When one joule of electrical energy is consumed by an appliance in one second, the power of the appliance is called one watt.
Relation between kWh and Joule 1 kWh = 1000Wh =1000 x 3600Ws = 3.6x106 joule.
Commercial unit of electricity The commercial unit of electricity is called kilowatt-hour (kWh). It is commonly known as unit. 1kWh is the energy consumed by an appliance when 1 kilowatt power is used per second.
Electricity consumed = Power x Time => E = P.t
Formulae used in this chapter
Q=It, V=IR, W=VQ
P = W / t = VQ/ t = VI = IR.I = I2R = V2/R
H = I2Rt, R=R1+R2+R3, 1/R = 1/R1+1/R2+1/R3, E = P .t
Find the resultant resistances in the following circuit diagrams -
