# IFS (Forests Services) Physics (Mains): Questions 1 - 5 of 34

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## Question number: 1

» Thermal and Statistical Physics » Statistical Physics » Bose-Einstein Condensation

Appeared in Year: 2011

### Write in Short

Write down the expression for the Bose – Einstein distribution function and explain the meaning of the symbols used. (Paper-I) (Section - B)

## Question number: 2

» Classical Mechanics » Particle Dynamics » Conservation of Linear and Angular Momentum

Appeared in Year: 2011

### Write in Short

A particle of rest mass ‘M’ moving at a velocity ‘u’ collides with a stationary particle of rest mass ‘m’. If the particle stick together, show that the speed of the composite ball is equal to,

Where (Paper-1) (Section –A)

## Question number: 3

» Quantum Mechanics II & Atomic Physics » Atomic Physics » Spectroscopic Notation of Atomic States

Appeared in Year: 2011

### Describe in Detail

Obtain the term symbols for two singlet states and two triplet states for two electron atoms. (Paper-2) (Section-A)

### Explanation

If we knowing the value of various types of angular momenta, term symbols gives three kinds of information,

Total orbital angular momentum, L

Multiplicity of the terms,

Total angular momentum,

- We

## Question number: 4

» Classical Mechanics » System of Particles » Generalised Coordinates and Momenta

Appeared in Year: 2012

### Describe in Detail

Using D’ Alembert’s principle, show that the following relation can be obtained for a system of particles under generalized coordinates,

What is the significance of ? (Paper-1) (section – A)

### Explanation

- The mathematical statement of D’ Alembert’s principle is given as,

- Transform D’ Alembert’s principle into expressions containing independent generalized coordinates only.

- Equation (2), gives an infinitesimal virtual displacement at particular instant . We can see that the variation with respect to time is absent in equation

## Question number: 5

» Classical Mechanics » System of Particles » Cyclic Coordinates

Appeared in Year: 2012

### Write in Short

Express Lagrange’s equation of motion for the cyclic coordinate and show that the result leads to the general conservation theorem for the generalized momentum coordinates. (Paper - 1) (Section – A)