Vacuum tubes (Diode and Triode) MCQ Basic Level

Vacuum tubes (Diode and Triode) MCQ Basic Level

Dear Readers,

Physics is an important subject in preparation for various Competitive exams.To keep a track of your preparation we have designed a small quiz of 10 Basic Level Questions on Vacuum tubes (Diode and Triode). You have 10 minutes to solve the quiz, click the start timer button in order to start the timer and then click on submit button at the end to submit the quiz and view your scores and correct answers..

Q1. Thermionic emission from a heated filament varies with its temperature T as :

•  T ^-1
•  T
•  T ²
•  T ^3/2

Solution
Answer: T ²

Q2.Number of secondary electrons emitted per number of primary electrons depends on:

•  Material of target
•  Frequency of primary electrons
•  Intensity
•  None of the above

Solution
Answer: Intensity

Q3.  Due to S.C.R in vacuum tube :

•   I _p Decrease
•   I _p Increase
•   V _p Increase
•   V _g Increase

Solution
Answer: I _p Decrease

Q4. In diode, when there is saturation current, the plate resistance is

•   Zero
•   Infinite
•   Some finite quantity
•   Data is insufficient

Solution
Answer: Infinite

Q5.   The grid voltage of any triode valve is changed from –1 volt to – 3 volt and the mutual conductance is 3 X 10 ^-4 mho. The change in plate circuit current will be

•  0.8 mA
•   0.6 mA
•   0.4 mA
•  1 mA

Solution
 Answer: 0.6mA

Q6. For a given plate-voltage, the plate current in a triode is maximum when the potential of :

•   The grid is positive and plate is negative
•  The grid is positive and plate is positive
• The grid is zero and plate is positive
•   The grid is negative and plate is positive

Solution
Answer: B

Q7. The amplification factor of a triode is 20. If the grid potential is reduced by 0.2 volt then to keep the plate current constant its plate voltage is to be increased by

•   10 volt
•   4 volt
•   40 volt
•   100 volt

Solution
Answer :B

Q8.The amplification produced by a triode is due to the action of:

•   Filament
•  Cathode
•   Grid
•  Plate

Solution
Answer: C

Q9.In an experiment, the saturation in the plate current in a diode is observed at 240V. But a student still wants to increase the plate current. It can be done, if

•  The plate voltage is increased further
•   The plate voltage is decreased
•  The filament current is decreased
•  The filament current is increased

Solution
Answer: D

Q10.  In a triode amplifier, the value of maximum gain is equal to

•  Half the amplification factor
•  Amplification factor
•  Twice the amplification factor
• Infinity

Solution
Answer: B