GATE (Graduate Aptitude Test in Engineering) Physics: Questions 277  279 of 622
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Question number: 277
» Solid State Physics » Defects in Crystals
Appeared in Year: 2010
Question
The Bloch theorem states that within a crystal, the wavefunction, of an electron has the from –
Choices
Choice (4)  Response  

a.  where , is a lattice vector and is an arbitrary vector 

b.  , where is an arbitrary function and is an arbitrary vector 

c.  where is an arbitrary function and is a reciprocal lattice vector 

d.  where , is a lattice and is a reciprocal lattice vector 

Question number: 278
» Mathematical Physics » Elementary Ideas About Tensors » Covariant and Contravariant Tensor
Appeared in Year: 2010
Question
Consider an anti – symmetric tensor with the indices and running from to . The number of independent components of the tensor is –
Choices
Choice (4)  Response  

a.  3 

b.  10 

c.  6 

d.  9 

Question number: 279
» Atomic and Molecular Physics » Electronic Transition in Diatomic Molecules
Appeared in Year: 2010
Question
Two states of an atom have definite parities. An electric dipole transition between these states is
Choices
Choice (4)  Response  

a.  Allowed if both the states have even parity 

b.  Allowed if both the states have odd parity 

c.  Not allowed unless a static electric field is applied 

d.  Allowed if the two states have opposite parities 
