CBSE Electricity Subject Notes

CBSE Guess > eBooks > Class X > Electricity by Mr Sunil D Chauhan

Electricity

Electricity

How can we get the continuous flow of electric current?

We can get the continuous flow of electric current by maintaining the potential difference between the two ends of the conductor using a cell or a battery.

Ohm's law (Important condition for Ohm's Law is that the temperature must remain constant) According to Ohm's Law -'At constant temperature, the current flowing through the conductor is directly proportional to the potential difference across its ends'. If the current flowing through the conductor is 'I' and the potential difference across its ends is 'V', then

or V = IR I = V/R (R is constant)

R is called the resistance Its SI unit is ohm (?). Resistance is the property of a conductor that resists the flow of charge passing through it.
Factors affecting the resistance of a conductor. The resistance of a conductor -

1. Is directly proportional to the length of the conductor.
2. Is inversely proportional to the area of cross-section (or thickness).
3. Is directly proportional to the temperature.
4. Depends upon the nature of the material of the conductor.

One ohm When the potential difference across the ends of a conductor is 1 volt and the current passing through it is 1 ampere, then the resistance of the conductor is 1 ohm.

Therefore, 1 ohm = 1 volt / 1 ampere

How is current affected in Ohm's Law. The current flowing through a conductor is

1. Is directly proportional to the potential difference.
2. Is inversely proportional to the resistance.

Variable resistance The component which is used to regulate the current without changing the potential difference is called the variable resistance. It is represented by

Rheostat The device which is used to change the resistance in the circuit is called rheostat. The resistance in the circuit diagram isdenotedby

Resistance The ratio of the potential difference across the ends of a conductor to the current flowing through it is called the resistance. It is denoted by 'R' and denoted in circuit diagram by. Its SI unit is ohm (?).

Resistor is an object having resistance of desired value while resistance is the property due to which it opposes electric current.

The current flowing through different components is different because the different components retard the motion of electrons by different amount of resistances.

The component that offers a very low resistance is called a good conductor. The component that offers higher resistance is called a poor conductor. An insulator of same size offers a very-very high resistance.

Resistivity The ratio of the product of the resistance and the area of cross-section to the length of conductor is called resistivity of substance. Its SI unit is ohm^-m (?m).

1. Resistance of a conductor is directly proportional to its length(R l)
2. Resistance of a conductor is inversely proportional to the area of cross-section (R 1/A)



(rho) is called the resistivity or the specific resistance of a material.