Electrostatics and Semiconductors

If Np and Ne be the number of holes and electrons for conduction in an extrinsic semiconductor, then _

• Np>Ne

• Np<Ne

• Np=Ne

• Depends on the nature of dopant

Energy bands in solids are a consequence of _____.

• Heisenberg's Uncertainty Principle

• Einstein's Photoelectric effect

• Pauli's Exclusion Principle

• Avogadro's Hypothesis

n number of electric fields are acting on a point P located in 3-dimensional space.The resultant electric field 'E' is given by __.

• Geometric mean of individual electric fields

• Vector sum of individual electric fields

• Harmonic mean of individual electric fields

• Algebraic sum of individual electric fields

Two point charges +3 μC and +8 μC repel each other with a force of 40 N. If a charge of -5 μC is added to each of them, then the force between them will become

• -10 N

• +10N

• +20N

• None of these

A cylinder of radius R and length L is placed in a uniform electric field E parallel to the cylinder axis. The total Flux for the surface of the cylinder is given by

• 2 π R²E

• π R²/E

• ( π R²/ π R)/ E

• Zero

ABC is an equilateral triangle. Charged +q are placed at each corner. The electric field intensity at O will be

• __1__q__

  4 πε₀ r²

• q/(4 π ε₀ r)

• Zero

• 3q/(4 π ε₀ r²)

A proton and an electron are placed in a uniform electric field

• The electric forces acting on them will be equal

• The magnitude of the forces will be equal

• Their accelerations will be equal

• The magnitude of their accelerations will be equal

The electric field inside a spherical shell of uniform surface charge density is

• Zero

• Constant but less than zero

• Directly proportional to the distance from the centre

• Inversely proportional to the square of the distance from the centre.

• None of the above

The charge given to any conductor resides only on its outer surface, because

• The free charge tends to be in its maximum kinetic energy state

• The free charge tends to be in its minimum potential energy state

• The free charge tends to be in its maximum potential energy state

• The free charge tends to be in its minimum kinetic energy state

Under the action of a given coulombic force the acceleration of an electron is 2.5×10²² m/s². Then the magnitude of acceleration of a proton under the same action of force is nearly

• 1.5 × 10-¹⁹ m/s²

• 9.1 × 10³¹ m/s²

• 1.6 × 10-¹⁹ m/s²

• 1.67 × 10²⁷ m/s²