Tag: electronic devices

Questions Related to electronic devices

The decimal number $16$ in binary number is

physics electronic devices boolean algebra digital electronics and logic gates logic gates

  1. $1000$

  2. $10000$

  3. $1010$

  4. $11000$

Show answer
Correct Option: B
Explanation:
 2  16  
 2  8  0
 2  4  0
 2  2  0
   1  0
   0  -1

$\uparrow$ read up the remainders
So, $(16)$$ _{10}$ $= (10000)$$ _2$

The binary number of decimal number $(9.25)$$ _{10}$ is

physics electronic devices boolean algebra digital electronics and logic gates logic gates

  1. $1101.01$

  2. $1001.01$

  3. $1001.10$

  4. $1110.010$

Show answer
Correct Option: B
Explanation:

$(9.25) _{10} = (9) _{10} + (0.25) _{10} = (1001) _2 + (0.01) _2 = (1001.01) _2$

Sum of the two binary number $(100010) _2$ and $(11011) _2$ is

physics electronic devices boolean algebra digital electronics and logic gates logic gates

  1. $(111101) _2$

  2. $(111111) _2$

  3. $(101111) _2$

  4. $(111001) _2$

Show answer
Correct Option: A
Explanation:

$100010 + 11011 = (111101) _2$

Which one of the following gives the $2's$ complement of decimal number $13$?

physics electronic devices boolean algebra digital electronics and logic gates logic gates

  1. $0010$

  2. $0011$

  3. $1100$

  4. $1101$

Show answer
Correct Option: B
Explanation:

The binary representation of $13$ is $1101$. The $1's$ complement of $13$ is $0010$. The $2's$ complement of $13$ is $0010 + 1 = 0011$.

The BCD code for the character A is

physics electronic devices boolean algebra digital electronics and logic gates logic gates

  1. $1000$

  2. $1010$

  3. $1011$

  4. $1100$

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Correct Option: B

A zener regulated power supply consists of a $9 V $ battery connected in series with a and a zener diode. The zener diode maintains a constant voltage drop of $4V $ The current drawn by the load resistance will be :

zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

  1. $0.025 A$

  2. $0.050 A$

  3. $0.01 A$

  4. $0.015 A$

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Correct Option: A

Zener breakdown takes place if:

zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

  1. Doped impurity is low

  2. Doped impurity is high

  3. Less impurity in N-part

  4. Less impurity in P-type

Show answer
Correct Option: B
Explanation:

 Zener breakdown occurs due to heavily doped diodes.In this process electrons crosses the barrier from 

the valence band of the p-type  to the conduction band of the lightly filled n-type material.

If, a Zener diode ($V _z = 5V$ and $I _z = 10 mA$) is connected in series with a resistance and 20 V is applied across the combination, then the maximum resistance one can use without spoiling zener action is

zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

  1. 20 $k\Omega$

  2. 15 $k\Omega$

  3. 10 $k\Omega$

  4. 1.5 $k\Omega$

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Correct Option: C

The main cause of Zener breakdown is

zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

  1. the base semiconductor being germanium.

  2. production of electron-hole pairs due to thermal excitation.

  3. low doping.

  4. high doping.

Show answer
Correct Option: D
Explanation:

Zener breakdown occurs in heavily doped p-n junctions. The heavy doping makes the depletion layer extremely thin. So that, carriers cannot accelerate enough to cause ionization. Thus, current will increase in reverse bias only due to reverse breakdown voltage.

The main cause of avalanche breakdown is

zener diode special purpose diodes electronic devices semiconductor electronics: materials, devices and simple circuits physics

  1. collision by ionisation.

  2. high doping.

  3. recombination of electrons and holes.

  4. low doping.

Show answer
Correct Option: A
Explanation:

Avalanche breakdown is caused by impact ionization of electron-hole pairs. A very little current flows under reverse bias conditions and depletion region increases. The electric field in the depletion region of a diode can be very high. Electron/holes that enter the depletion region undergo a tremendous acceleration. As these accelerated carriers collide with the atoms, they can knock electrons from their bonds, creating additional electron/hole pairs and thus additional current. As these secondary carriers are swept into the depletion region, they too are accelerated and the process repeats itself.