Students must go through these JAC Class 10 Science Notes Chapter 12 Electricity to get a clear insight into all the important concepts.
JAC Board Class 10 Science Notes Chapter 12 Electricity
→ Electric charge: An electric charge is an intrinsic property of the proton, electron and many other particles. There are two types of electric charges :
- Positive electric charge
- Negative electric charge.
→ Electric current: The electric current is the net amount of electric charge that passes through any cross-sectional area of the conductor in unit time (I = \(\frac { Q }{ t }\)).
Its SI unit is the coulomb/second (C/s) or the ampere (A).
The direction of the conventional current is taken as opposite to the direction of the flow of electrons.
ampere: If 1 coulomb charge flows through any cross-section of a conductor in 1 second, then the electric current flowing through the conductor is said to be 1 ampere.
1 mA = 10-3 A, 1 μA = 10-6A
→ Electric potential and Electric potential difference: The work done in bringing a unit positive charge from infinity to a particular point in the electric field against the electrostatic force due to the electric field is called the electric potential at that point.
(The charge is kept in equilibrium.)
The electric potential difference (p.d.) between any two points A and B in an electric field is the work done to move a unit positive charge ( + 1C) from one point A to the another point B against the electric force due to the electric field.
The SI unit of potential and potential difference is the joule /coulomb or volt (V).
→ volt: The potential difference between two points in an electric field is said to be 1 volt if 1 J of work is done to move a charge of 1 C from one point to another point.
1 V = \(\frac { 1 J }{ 1 C }\)
→ Ohm’s law: The current flowing through a conductor, such as a metallic wire, is directly proportional to the potential difference across its ends, provided its temperature and other physical conditions remains the same.
→ Resistance: Whenever a current flows through a conductor, the free electrons moving in one direction in the conductor collide with the ions, atoms and molecules of the conductor. Due to these collisions, the motion of electrons is opposed. The resulting opposition to the current is called resistance of the conductor.
Resistance R = \(\frac { V }{ I }\)
where, V = voltage applied between the two ends of the conductor
I = electric current flowing through the conductor
Unit: The SI unit of resistance is Ohm. It is denoted by Ω (omega).
Ohm : If the potential difference across the two ends of a conductor is 1V and the current through it is 1 A, then the resistance R of the conductor is 1Ω.
1 Ω = \(\frac { 1 V }{ 1 A }\)
→ Resistivity: The electrical resistivity of a material is the resistance of a conductor (of that material) having unit length and unit area of cross-section. Its SI unit is Ωm.
→ Series combination of resistors: When two (or more) resistances are connected end to end consecutively with one source such that the close path is formed, then they are said to be connected in series.
OR
When two or more than two resistors are connected between two points in a circuit in such a way that the current has only one way to flow and current flowing through every resistor in the circuit remains the same, such a combination of the resistors is called series combination of resistors.
The total resistance of the circuit increases in a series combination of resistors. This results in a reduction in the current.
→ Parallel combination of resistors: When two (or more) resistances and one source are connected between the same two points, they are said to be connected in parallel.
OR
When two or more than two resistors are connected between two points in a circuit in such a way that more than one paths are available for the current to flow and the voltage drop across two ends of each resistor remains the same, then the resistors are said to be connected in parallel between these two points and the combination of resistors is called parallel combination.
The total resistance in the circuit is reduced in a parallel combination of the resistors. This results in an increase in the electric current.
→ Heating effect of electric current: The production of heat in a metallic conductor by the electric current flowing through it is callled the heating effect of electric current.
The heat generated due to flow of electric current depends on the following factors:
- Electric current
- Resistance and
- Time taken to pass electric current.
The electrical energy consumed (or heat energy produced) when an electric current (7) flows in a conductor for time t is
H = I²Rt = \(\frac{V^2}{R}\) t = \(\frac { V }{ R }\) x Vt = IVt (joule)
The unit of electric energy is joule.
→ Electric power: Electric energy consumed (or heat energy produced) per unit time is termed as electric power.
OR
Electric power is the rate of consumption of electric energy with time. The SI unit of electric power is watt.
watt: If a device carries a current of 1 A when operated at a potential difference of 1 V, the power consumed is 1W.
1 watt = 1 volt x 1 ampere.