 # Physics II

## Find the value of half-life period.

Value of Half-Life Period From the law of radioactive disintegration, we know, If,  be the half life period, then at, ,

## Deduce the law of radioactive disintegration.

The Law of Radioactivity Disintegration: Let, N be the number of atoms present in the radio element at a given instant t. Then the rate of decrease, Here, λ is the disintegration constant. It is defined as the ratio of the amount of the substance which disintegrates in a unit time to the amount of …

## Describe the general properties of nucleus.

General Properties of Nucleus: (i) Nuclear Size: From Rutherford’s work, the mean radius of nucleus is  and the radius of the atom is . Thus the radius of the nucleus is 10,000 times smaller than the radius of the atom. The empirical formula for the nuclear radius is, Here, A is the mass number,  is a constant. From …

## Derive the de Broglie wavelength for a charged particle of charge q and accelerated through a potential difference of V volts.

The Required de Broglie Wavelength: A photon of light of frequency  has the momentum, But, . Therefore, the momentum of the photon can be expressed in terms of wavelength λ as, The wavelength of a photon is, therefore, specified by its momentum according to the relation, de Broglie suggested that the above equation is applicable for any …

## Derive the Einstein’s photoelectric equation.

Einstein’s Photoelectric Equation :  According to Einstein, light of frequency  consists of a shower of photons, is of energy . When a photon of light of frequency  is incident on a metal, a part of the energy acquired by the electron is used to pull out the electron from the surface of the metal and the rest of …

## What do you mean by electric flux or flux of the electric field?

Electric Flux For an arbitrary closed surface, the net outward flow or flux is the product of the average outdrawn normal component of the vector and the area of surface. Electric flux is used to express the relation between  and its source. Flux is denoted by   = (average normal component)×(surface area) The unit of electric flux …

## What is flux?

Flux If  is a vector field, then the flux through any face is defined as the scalar product of the vector area of the face and the vector . That is, Flux = (component of velocity normal to the face) × (area of the face)          The amount of flux per unit area is …

## What is electric charge?

Electric Charge The reason present in a material causes static electricity, electric field in the material and the material become able to attract other materials is called electric charge. It may be positive or negative. Unit of electric charge is coulomb (C).

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