# Quantum Mechanics II & Atomic Physics (IFS (Forests Services) Physics (Mains)): Questions 1 - 2 of 2

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## Question number: 1

» 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 can do vector sums of these vector. But it becomes easy if we …

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## Question number: 2

» Quantum Mechanics II & Atomic Physics » Quantum Mechanics II » The Spin Half Problem and Properties of Pauli Spin Matrices

Appeared in Year: 2011

### Describe in Detail

What are Pauli spin matrices?

Show that:

Where, are Pauli spin matrices and and are vector operators which commute with , but do not necessarily commute with each other?

### Explanation

Pauli spin matrices or Pauli matrices are a set of matrices, which are complex, Hermitian and unitary matrices. Pauli spin matrices defined as,

The Pauli vector is defined by,

From question another vector operators are and are given.

Now, mapping mechanism from a Pauli matrix basis and a vector operator basis are provided as,

Simila…

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