246. A 4.7 zener has a resistance of 15Ω. When a current 20 mA passes through it, then the terminal voltage is—

1. 1. 5 V

   
   
   

   2. 10 V

   
   
   

   3. 15 V

   
   
   

   4. 20 V

   
   
   

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1. View Hint View Answer Discuss in Forum

   The terminal voltage,
   V’_z = V_z + I_z rz
   or V’_z = 4.7 + 20 × 10–3 × 15
   or V’_z = 4.7 + 0.3 = 5 V

   
   

   Correct Option: A

   The terminal voltage,
   V’_z = V_z + I_z rz
   or V’_z = 4.7 + 20 × 10–3 × 15
   or V’_z = 4.7 + 0.3 = 5 V

   
   

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247. When a reverse current in a zener diode increases from 20mA to 30 mA, the zener voltage changes from 5.6 V to 5.65 V. The zener resistance is—

1. 1. 2 Ω

   
   
   

   2. 3 Ω

   
   
   

   3. 4 Ω

   
   
   

   4. 5 Ω

   
   
   

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1. View Hint View Answer Discuss in Forum

   RZ =		∆VZ	=	5.65 – 5.6	= 5Ω
   		∆IZ		(30 – 20) mA

   Correct Option: D

   RZ =		∆VZ	=	5.65 – 5.6	= 5Ω
   		∆IZ		(30 – 20) mA

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248. A zener diode has a dc power dissipation rating of 500 mW and a zener voltage rating of 7.5 V. The value of IZM is—

1. 1. 70 mA

   
   
   

   2. 66.67 mA

   
   
   

   3. 86.67 mA

   
   
   

   4. 76.67 mA

   
   
   

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1. View Hint View Answer Discuss in Forum

   Izm =		PZ	=	500 mW	= 66.67 mA
   		VZ		7.5 V

   Correct Option: B

   Izm =		PZ	=	500 mW	= 66.67 mA
   		VZ		7.5 V

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249. Zener diode is used as—
     

1. 1. An ampifier

   
   
   

   2. A voltage regulator

   
   
   

   3. A rectifier

   
   
   

   4. A multivibrator

   
   
   

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1. View Hint View Answer Discuss in Forum

   Zener diode is used as a voltage regulator
   

   Correct Option: B

   Zener diode is used as a voltage regulator
   

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250. In avalanche multiplication—

1. 1. Distribution of covalent bond occurs by collision

   
   
   

   2. Direct rupture of bonds

   
   
   

   3. Both (A) and (B)

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   In avalanche multiplication distribution of covalent bond occurs by collision.
   

   Correct Option: A

   In avalanche multiplication distribution of covalent bond occurs by collision.
   

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