Electric Current
The flow of electric charge is known as Electric Current, Electric current is carried by moving electrons through a conductor. By convention, electric current flows in the opposite direction to the movement of electrons.
Electric Circuit
Electric circuit is a continuous and closed path of electric current.
Ammeter
An apparatus to measure electric current in a circuit.,
Charge
Like mass, the charge is the fundamental property of matter. There are two types of charge
(i) Positive charge. (ii) Negative charge.
Properties of Electric Charge:
(i) Unlike charges attract each other and like charges repel each other.
(ii) The.force between two charges varies directly as the product of two charges and inversely as the square of the distance (r) between both charges (q1 and q2).
S.I.
unit of charge is coulomb (C).
1 coulomb = 1 ampere × 1 second.
1C = 1A × 1s
Thus, the quantity of charge which flows through a circuit when one ampere of current flows through it in one second is known as a 1-coulomb charge.
Ohm’s Law
Ohm’s Law states that the potential difference between two points is directly proportional to the electric current, at a constant temperature.
This means potential difference V varies as electric current.
V ∝ I
V = RI
I = VR
R = VI
Where, R is constant for the given conductor at a given temperature and is called resistance.
1 Ohm
1 ohm (Q) of resistance (R) is equal to the flow 1A of current through a conductor between two points having a potential difference equal to 1V.
This means; 1Ω = 1V/1A
The topics discussed in this chapter are as follows:
- Conductors and Insulators
- Models of Electric Current
- Electric Circuit
- Resistance and Ohm's Law
- Combination of Resistors
- Electric Power and AC
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NCERT Solutions for Chapter 12: Electricity
Also Check
Chapter 1: Chemical Reactions and Equations
Chapter 2: Acids, Bases and Salts
Chapter 3: Metals and Non-Metals
Chapter 4: Carbon and its compounds
Chapter 5: Periodic Classification of Elements
Chapter 6: Life Processes
Chapter 7: Control and Coordination
Chapter 8: How do organisms reproduce?
Chapter 9: Heredity and Evolution
Chapter 10: Light - Reflection and Refraction
Chapter 11: The Human Eye and the Colourful World
Chapter 13: Magnetic Effects of Electric Current
Chapter 14: Sources of Energy
Chapter 15: Our Environment
Chapter 16: Sustainable Management of Natural Resources
Check out Frequently Asked Questions (FAQs) for Chapter 12: Electricity
What are resistors? Give some examples.
Why is an electric bulb filled with argon and nitrogen gas?
State the Joule’s law of heating.
Joule’s law of heating states that the heat produced in a resistor is directly proportional to
- Square of current (I2)
- Resistance of the resistor (R) and
- Time for which the current flows through the resistor.
H = I2Rt joules
From Ohm’s law, we get H = VIt joules = v2t/R joules
What is the shape of the graph obtained by plotting potential difference applied across a conductor against the current flowing through it?
Why are copper and aluminium wires usually employed for electricity transmission?
Copper and aluminium have low resistivities. When electricity is transmitted through copper and aluminium wires, the power losses in the form of heat are very small.
