266. The value of wave number may be:

1. 1. zero

   
   
   

   2. positive

   
   
   

   3. negative

   
   
   

   4. all of the these

   
   
   

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1. View Hint View Answer Discuss in Forum

   The value of wave number may be
   * Zero
   * Positive
   * Negative

   Correct Option: D

   The value of wave number may be
   * Zero
   * Positive
   * Negative

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267. Resistance R of intrinsic semiconductor is:

1. 1. ∝ T K

   
   
   

   2. ∝		1		K
      		T

   
   
   

   3. ≠ T K

   
   
   

   4. = R_0^eEg/kT

   
   
   

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1. View Hint View Answer Discuss in Forum

   Resistance R of intrinsic semiconductor is
   R = R_0^eEg/kT
   where, R₀ = Resistance at 0 K
   E_g = Energy band gap
   k = Boltzmann’s constant
   T = Temperature

   Correct Option: D

   Resistance R of intrinsic semiconductor is
   R = R_0^eEg/kT
   where, R₀ = Resistance at 0 K
   E_g = Energy band gap
   k = Boltzmann’s constant
   T = Temperature

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268. At 0 K, an extrinsic semiconductor behaves like a:

1. 1. perfect insulator

   
   
   

   2. good conductor

   
   
   

   3. superconductor

   
   
   

   4. metal

   
   
   

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1. View Hint View Answer Discuss in Forum

   At 0 K, an extrinsic semiconductor behaves like a perfect insulator.

   Correct Option: A

   At 0 K, an extrinsic semiconductor behaves like a perfect insulator.

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269. Two important semiconductors Ge and Si have:

1. 1. 4 valence electrons

   
   
   

   2. 3 valence electrons

   
   
   

   3. 1 valence electron

   
   
   

   4. 5 valence electrons

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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270. A material having different properties in different directions is known as:

1. 1. isotropic

   
   
   

   2. anisotropic

   
   
   

   3. crystalline

   
   
   

   4. metal

   
   
   

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1. View Hint View Answer Discuss in Forum

   A material having different properties in different directions is known as anisotropic.

   Correct Option: B

   A material having different properties in different directions is known as anisotropic.

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