If the lattice parameter for a crystalline structure is $3.6<mspace\; width="1em"></mspace>\stackrel{0}{A},$ then the atomic radius in fcc crystal is

1. $1.81\stackrel{0}{A}$

2. $2.10\stackrel{0}{A}$

3. $2.92\stackrel{0}{A}$

4. $1.27\stackrel{0}{A}$

A p-n photodiode is made of a material with a band gap of 2.0 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly

1. $10\times {10}^{14}<mspace\; width="1em"></mspace>Hz$                             
2. $5\times {10}^{14}<mspace\; width="1em"></mspace>Hz$
3. $1\times {10}^{14}<mspace\; width="1em"></mspace>Hz$                               
4. $20\times {10}^{14}<mspace\; width="1em"></mspace>Hz$

The electrical resistance of depletion layer is large because:

1. It has no charge carriers

2. It has a large number of charge carriers

3. It contains electrons as charge carriers

4. It has holes as charge carriers

Avalanche breakdown is due to 

(1) Collision of minority charge carrier

(2) Increase in depletion layer thickness

(3) Decrease in depletion layer thickness

(4) None of these

In a crystal, the atoms are located at the position of

(1) Maximum potential energy

(2) Minimum potential energy

(3) Zero potential energy

(4) Infinite potential energy

The distance between the body centered atom and a corner atom in sodium (a = 4.225 Å) is 

(1) 3.66 Å

(2) 3.17 Å

(3) 2.99 Å

(4) 2.54 Å

In good conductors of electricity, the type of bonding that exists is 

(1) Ionic

(2) Vander Waals

(3) Covalent

(4) Metallic

In an insulator, the forbidden energy gap between the valence band and conduction band is of the order of

(1) 1  MeV

(2)  0.1 MeV

(3) 1 eV 

(4) 15 eV

The energy band gap of Si is

(1) 0.70 eV

(2) 1.1 eV

(3) Between 0.70 eV to 1.1 eV

(4) 5 eV