When a wire is stretched to twice its original length, what happens to its resistivity?

The resistivity of the wire stays the same, as it is a material property that does not depend on the wire's dimensions.

What is the resistance of the connecting wire?

The resistance of a connecting wire, which is constructed from a highly conductive material, is negligible.

Why does an ammeter burn out when connected in parallel?

An ammeter, which is designed with a low resistance, burns out when connected in parallel because a large amount of current flows through it, causing it to overheat and potentially short-circuit..

Why are alloys preferred over pure metals in electrical heating devices?

Alloys are preferred over pure metals in electrical heating devices because they have higher resistivity, which results in greater heat production. Additionally, alloys are more resistant to burning or oxidation at elevated temperatures.

What factors influence the resistance of a conductor?

Resistance depends on the following factors R ∝ l(length of conductor); R ∝ 1/A(Area of cross-section); R ∝ T(Temperature) R depends on the nature of material.

CBSE Notes

Class 10

Science

Chapter 11 Electricity

CBSE Notes Class 10 Science Chapter 11 - Electricity

Electricity is a fundamental form of energy vital to modern life. It involves the movement of electric charges, typically electrons, through conductors such as copper wires. This flow of electric charge constitutes an electric current, which powers countless devices and systems.

Class 10 Science Chapter 11 Revision Notes:

1.0Electric Current and Circuit

It is the flow of charge through a conductor. The electric current I is referred to as the charge Q passing through a point in a circuit per unit time.

I = Qt. Ampere is the SI Unit of current(A).Current is a scalar quantity.

Electricity is categorized into:

Static Electricity: Concerns stationary charges.

Current Electricity: Involves moving charges.

Electric charge is a property of matter responsible for electric and magnetic effects. Coulomb is the practical SI Unit of Electric Charge, and it is also a scalar quantity.

Properties of Electric Charge

Like charges repel; unlike charges attract.
Charge is conserved and additive.
Charge is quantized, meaning it exists in discrete amounts.

2.0Circuits

A circuit is a closed loop that permits the flow of electric current. It typically includes components such as resistors, capacitors, and power sources.

3.0Electric Potential and Potential Difference

Electric Potential (V): The work done per unit positive charge to move it from infinity to a point in an electric field: V=WQ0

Electric potential is measured in volts (V), where 1 Volt = 1 Joule/Coulomb (J/C). It is a scalar quantity and can be positive or negative.

V = WQ0

Potential Difference-The work done to move a unit charge from one point to another in a circuit: V = WQ0

One volt is the potential difference that results when one joule of work is done to move one coulomb of charge between two points.

4.0Ohm’s Law

Ohm’s Law states that the current through a conductor is directly proportional to the potential difference across it, provided the temperature remains constant:

V $\propto$ I

or V = RI

or V/I = R

Where, R = Resistance of the conductor which is a constant

SI Unit of Resistance: Ohm (Ω). 1 Ohm is the resistance when 1 Volt is applied, and 1 Ampere of current flows through the conductor.

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