Materials and Components

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Assertion (A): Doping level in extrinsic semiconductors is very small.Reason (R): Additional of impurity in the ratio of 1 part in 108 parts increases the number of charge carriers by about 20.

Assertion (A):  Doping level in extrinsic semiconductors is very small.Reason (R):  Additional of impurity in the ratio of 1 part in 108 parts increases the number of charge carriers by about 20.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option A

Assertion (A): Electron concentration n, hole concentration p and charge concentration ni are related by ni2 = np.Reason (R): p type semiconductor is obtained by adding trivalent impurity to intrinsic semiconductor.

Assertion (A):  Electron concentration n, hole concentration p and charge concentration ni are related by ni2 = np.Reason (R): p type semiconductor is obtained by adding trivalent impurity to intrinsic semiconductor.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option B

Assertion (A): Hall effect is used to determine whether the semi- conductor is p or n type.Reason (R): Under the influence of field, holes and electrons move in opposite direction.

Assertion (A):  Hall effect is used to determine whether the semi- conductor is p or n type.Reason (R):  Under the influence of field, holes and electrons move in opposite direction.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option A

Assertion (A): Silicon is the most favoured semiconductor material.Reason (R): PIV for silicon diode is more than that for germanium diode.

Assertion (A):  Silicon is the most favoured semiconductor material.Reason (R):  PIV for silicon diode is more than that for germanium diode.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option C

Assertion (A): Silicon is less sensitive to changes in temperature than germanium.Reason (R): Cut in voltage in silicon is less than that in germanium.

Assertion (A):  Silicon is less sensitive to changes in temperature than germanium.Reason (R):  Cut in voltage in silicon is less than that in germanium.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option C

Assertion (A): Holes are majority carriers in p type semiconductor.Reason (R): In p type semiconductor, the electrons produced by thermal agitation recombine with holes.

Assertion (A):  Holes are majority carriers in p type semiconductor.Reason (R):  In p type semiconductor, the electrons produced by thermal agitation recombine with holes.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option A

Assertion (A): Acceptor extrinsic semiconductor has higher conductivity than intrinsic semiconductor.Reason (R): Addition of p-type impurity produces an allowable discrete energy level just above valence band.

Assertion (A):  Acceptor extrinsic semiconductor has higher conductivity than intrinsic semiconductor.Reason (R):  Addition of p-type impurity produces an allowable discrete energy level just above valence band.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option A

Assertion (A): Intrinsic resistivity of silicon is lower than that of germanium.Reason (R): Magnitude of free electron concentration in germanium is more than that of silicon.

Assertion (A):  Intrinsic resistivity of silicon is lower than that of germanium.Reason (R):  Magnitude of free electron concentration in germanium is more than that of silicon.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option D

Assertion (A): In an intrinsic semiconductor J = (μn x μp)eni.Reason (R): Intrinsic charge concentration ni at temperature T is given by ni2 = A0 T3 e-EG0/kT.

Assertion (A):  In an intrinsic semiconductor J = (μn x μp)eni.Reason (R):  Intrinsic charge concentration ni at temperature T is given by ni2 = A0 T3 e-EG0/kT.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option B

Assertion (A): When cathode temperature is increased from 2500 K to 2550 K, thermionic emission current may increase by about 50%.Reason (R): Thermionic emission current ∝ T2 e-Ew/kT.

Assertion (A):  When cathode temperature is increased from 2500 K to 2550 K, thermionic emission current may increase by about 50%.Reason (R):  Thermionic emission current ∝ T2 e-Ew/kT.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option A

Assertion (A): At a temperature of 1000 K, thermionic emission current is about 0.1 A/cm2 of surface.Reason (R): Thermionic emission current is given by Ith = SA0 T2 e-Ew/kT.

Assertion (A):  At a temperature of 1000 K, thermionic emission current is about 0.1 A/cm2 of surface.Reason (R):  Thermionic emission current is given by Ith = SA0 T2 e-Ew/kT.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option A

Assertion (A): For most metals, Fermi energy EF is less than 10 eV.Reason (R): Fermi level of a metal is given by EF = 3.64 x 10-19 (n)2/3 where n is number of free electrons/m3 of metal.

Assertion (A):  For most metals, Fermi energy EF is less than 10 eV.Reason (R):  Fermi level of a metal is given by EF = 3.64 x 10-19 (n)2/3 where n is number of free electrons/m3 of metal.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option A

Assertion (A): Power loss in a conductor of resistance P = I2R.Reason (R): When a conductor is carrying current with current density J as a result of applied field E, then heat developed/m3/ second = JE.

Assertion (A):  Power loss in a conductor of resistance P = I2R.Reason (R):  When a conductor is carrying current with current density J as a result of applied field E, then heat developed/m3/ second = JE.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option A

Assertion (A): Resistivity of a perfect single crystal of a metal goes to zero as T approaches zero.Reason (R): Scattering of electrons is due to deviations from perfect periodicity of lattice.

Assertion (A):  Resistivity of a perfect single crystal of a metal goes to zero as T approaches zero.Reason (R):  Scattering of electrons is due to deviations from perfect periodicity of lattice.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option B

Assertion (A): Relaxation time and mean time between collisions are equal when scattering is isotropic.Reason (R): Mean free path of an electron λ, velocity of electron v and mean time between collisions tc are related as λ = vTc.

Assertion (A):  Relaxation time and mean time between collisions are equal when scattering is isotropic.Reason (R):  Mean free path of an electron λ, velocity of electron v and mean time between collisions tc are related as λ = vTc.
  • A. Both A and R are true and R is correct explanation of A
  • B. Both A and R are true but R is not correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true
  • Correct Answer: Option B
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