Daily life science queries – 8

Q:- Why does a ball bounce up upon falling?

Ans:- According to the Newton’s third law, to every action there is equal and opposite reaction.

When a ball falls, it is temporarily deformed. Because of elasticity, the ball tends to regain its original shape for which it presses the ground and bounces up (due to the Newton’s Third Law of motion)

Q:- Why do we perspire on a hot day? Continue reading “Daily life science queries – 8”

HEAT DEVELPOED IN A CURRENT CARRYING CONDUCTOR

Let us discuss the heat developed in a current carrying conductor and derive a relation for the same.

According to Joule’s law, the heat developed in a conducting wire is given by I2 R,

Where I is current flowing through the wire having resistance R.

If p is the electrical resistivity of wire,

L is the length of wire and

A is the area of cross section of wire Continue reading “HEAT DEVELPOED IN A CURRENT CARRYING CONDUCTOR”

CLASSIFICATION OF MATERIALS ON THE BASIS OF CONDUCTIVITY

CLASSIFICATION OF MATERIALS ON THE BASIS OF CONDUCTIVITY

On the basis of conductivity ,the materials can be classified in to following categories:-

(a)    Conductors:- These are those materials whose electrical conductivity is very high. Conductors conduct charges very easily . For super-conductor , the value of electrical conductivity is infinite.

Examples. Copper,Silver.Aluminum,Tungsten etc. Continue reading “CLASSIFICATION OF MATERIALS ON THE BASIS OF CONDUCTIVITY”

Clausius Mossotti equation

STATIC DIELECTRIC CONSTANTS OF SOLIDS

As discussed in the previous articles,the dielectric polarization can be considered to arise from three major sources:

Electronic ,ionic and orientational (dipolar) polarizations ,that is

Ptotal =Pe+Pi+P0

Thus, the materials may be classified into three types according to the dielectric behaviour of solids is concerned : Continue reading “Clausius Mossotti equation”

Common daily life science queries – 7

Q:- Why stars twinkle?

Ans:-  Do you know the phenomenon of refraction? Refraction is the bending of light as it moves from one medium to another.

Our air has many layers. The light from a star reaches us after refraction as it passes through various layers of air. When the light passes through the earth’s atmosphere, it is made to bend by the layers of the air and it appears as if the stars are twinkle.

Q:- Why a person is pushed back slightly, when he fires a gun? Continue reading “Common daily life science queries – 7”

Matthiessen’s Rule

Electron Scattering and Matthiessen’s Rule

Matthiessen’s Rule:

The resistivity ρ of a metal containing small amount of impurities may be written as:

ρ = ρ0i+ ρ(T)                                                          (1)

Where ρ 0 is a constant which increases with increasing impurity content and ρ (T) is the temperature –dependent part of the resistivity.

Equation (1) is known as the Matthiessen’s rule

Explanation. Continue reading “Matthiessen’s Rule”