381. The beta (β) of a transistor may be determined directly from the plots of—

1. 1. V_CB versus i _C for constant values of I_E

   
   
   

   2. V_BC versus i _E for constant values of I_B

   
   
   

   3. V_CE vessus i _C for constant values of I_B

   
   
   

   4. V_BE versus i_B for constant values of V_CE

   
   
   

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1. View Hint View Answer Discuss in Forum

   The gain of transistor i.e., β may be determined directly from the V_CE versus i _C plot for constant values of I_B.

   Correct Option: C

   The gain of transistor i.e., β may be determined directly from the V_CE versus i _C plot for constant values of I_B.

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382. The JFET in the circuit shown in figure has an I_DSS = 10 mA and V_p = – 5 V. The value of the resistance R_S for a drain current I_DS = 6.4 mA is (select the nearest value)—
     
     
     

1. 1. 150 ohm

   
   
   

   2. 470 ohm

   
   
   

   3. 560 ohm

   
   
   

   4. 1 kilo ohm

   
   
   

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1. View Hint View Answer Discuss in Forum

   We know that
   

   IDS = IDSS		1 -	VGS		…(a)
   			VP

   
   given that, I_DS = 6.4 × 10^{– 3} amp
   V_P = – 5 V
   I_DSS = 10 × 10^{– 3} amp. V_GS =?
   

   6.4 × 10– 3 = 10 × 10– 3		1 -	VGS		2
   			- 5

   
   

   1 –	VGS	= √64 = .8
   	- 5

   
   or V_GS = – 1V
   Now, I^DS R^S = – V_GS = – (– 1 V)
   

   RS =	1	= 156
   	6.4 × 10–3

   
   Since 156 Ω is very close to 150 Ω.
   Hence alternative (A) is correct answer.

   Correct Option: A

   We know that
   

   IDS = IDSS		1 -	VGS		…(a)
   			VP

   
   given that, I_DS = 6.4 × 10^{– 3} amp
   V_P = – 5 V
   I_DSS = 10 × 10^{– 3} amp. V_GS =?
   

   6.4 × 10– 3 = 10 × 10– 3		1 -	VGS		2
   			- 5

   
   

   1 –	VGS	= √64 = .8
   	- 5

   
   or V_GS = – 1V
   Now, I^DS R^S = – V_GS = – (– 1 V)
   

   RS =	1	= 156
   	6.4 × 10–3

   
   Since 156 Ω is very close to 150 Ω.
   Hence alternative (A) is correct answer.

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383. The light-emitting diode (LED)—

1. 1. Is usually made from silicon

   
   
   

   2. Uses a reverse-bised junction

   
   
   

   3. Given a light output which increases in temperature

   
   
   

   4. Depends on the recombination of holes and electrons

   
   
   

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1. View Hint View Answer Discuss in Forum

   The basic phenomenon of light emitting diode (LED) depends on the recombination of holes and electrons.

   Correct Option: D

   The basic phenomenon of light emitting diode (LED) depends on the recombination of holes and electrons.

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384. A zener diode—

1. 1. Has a high forward-voltage rating

   
   
   

   2. Has a sharp breakdown at low reverse voltage

   
   
   

   3. Is useful as an amplifier

   
   
   

   4. Has a negative resistance

   
   
   

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1. View Hint View Answer Discuss in Forum

   A zener diode has a sharp breakdown at low reverse voltage.

   Correct Option: B

   A zener diode has a sharp breakdown at low reverse voltage.

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385. In a Schmitt trigger using OP amplifiers the output is limited by diode clipper to V₀ = ± 8 volts. The positive input terminal voltage V₊ = β V₀, where β = 1 / 8. The signal V_s is applied to V–.
     The following statements (1) to (4) are made regarding V_s and V₊
     (1) For V_s negative and rising V₊ = + 1
     (2) For V_s positive and decreasing V₊ = + 1
     (3) For V_s decreasing through zero value V₊ = + 1
     (4) For V_s increasing though zero value V₊ = + 1
     Of these statements, the true statements are—

1. 1. 1 and 3

   
   
   

   2. 2 and 3

   
   
   

   3. 1 and 4

   
   
   

   4. None of these statements

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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