Free Online Practice test on Electronics

Free Online Practice test  on Electronics
Free Electronics Online Practice Test
Free Online Electronic Engineering Practice and Preparation test
1. UPS is
a. Uninterrupted power supply
b. Unlimited power supply
c. United power supply
d. None of these
Ans. a
2. UPS is a device which maintains continuous supply of ______ to the system connected
a. Electric power
b. Magnetic power
c. EMF
d. Resistance
Ans. a
3. _________ Supplies power when utility is not available.
a. AC mains
b. DC mains
c. UPS
d. SMPS
Ans. C
4. Types of UPS are
a. Switch on and offline UPS
b. Off line and on line UPS
c. Standard and normal ups
d. Power UPS
Ans. b
5. Diode is a combination of
a. Two electrons
b. Two electrodes
c. Two elements
d. Two capacitors
Ans. b
6. How many types of crystal diode rectifiers are there?
a. 2
b. 3
c. 4
d. 5
Ans. a
7. In half wave rectification, the rectifier conducts current only in _____of input ac supply.
a. Positive half cycle
b. Negative half cycle
c. Neutral
d. Both a and b
Ans. a
8. RMS value of current in half wave rectifier is
a. Im/?2
b. Im/2
c.2Im/Em
d. Em/2
Ans b
9. The transformer isolates the rectifier circuit form power line and thus reduces
a. Electric shock
b. Current loss
c. Resistance loss
d. Transformer
Ans. a
10. The pulsations in the output are further smoothening with the help of _________circuit.
a. Transformer
b. Diode
c. Filter
d. Transistor
Ans. c
11. The ratio of dc power output to the applied input of rectifier is known as
a. Power
b. Rectification efficiency
c. Utility factor
d. Working efficiency
Ans. b
12. In half wave rectification, a maximum of _______of ac power is rectifier.
a. 40%
b. 40.6%
c. 40.9%
d. 80.1%
Ans. b
13. The rectifier which contains 2 diodes is called
a. Full wave rectifier
b. Half wave rectifier
c. Centre – tap rectifier Full wave rectifier
d. Bridge full wave rectifier
Ans. c
14. Bridge full wave rectifier consists of ………… number of diodes.
a. 2
b. 3
c. 4
d. 6
Ans. c
15. The efficiency of full wave rectifier is
a. 40%
b. 40.6%
c. 81.2%
d. 80% Ans. c
16. A power supply which maintains the voltage constant irrespective of ac main fluctuations or load variations is known as
a. DC power supply
b. DC regulated power supply
c. Steady power supply
d. None of these
Ans. B
17. A dc regulate supply uses a for power regulation.
a. Transformer
b. Transistor
c. Capacitor
d. Zener diode
Ans. d
18. The process in which an ac voltage is converted into a unidirectional dc voltage is known as
a. Rectification
b. Conversion
c. Transformation
d. Regulation
Ans. a
19. When forward biased, junction diode offers
a. High resistance
b. Low resistance
c. No resistance
d. None of these
Ans. b
20. In the rectifier circuits the ac supply form mains is given through ______ for transformation.
a. Amplifier
b. Transformer
c. Diode
d. Load resistor
Ans. b
21. The ac supply to be rectified in half wave rectifier is applied in series with
a. Diode and load resistance
b. Load resistance and transformer
c. Diode and regulated power supply
d. Two diode
Ans. a
22. An AC rectifier which rectifies both the positive and negative ac half cycles of input wave are called
a. Half wave rectifier
b. Full wave rectifier
c. Transformation rectifier
d. None of these
Ans. b
23. In full – wave rectifier the direction of current in load resistor is ____________ for both half cycles of ac.
a. Opposite
b. Same
c. Different
d. None of these
Ans. b
24. The expression for peak inverse voltage, in case of centre – tap full wave rectifier is
a. 2Vm
b. Vm
c. Vm/2
d. 3Vm
Ans. a
25. In on line UPS ________ batteries are used earlier
a. semiconductor
b. ionic
c. Lead – acid
d. Ordinary
Ans. b
26. Large UPS units typically work in conjunction with
a. Motor
b. Batteries
c. Generator
d. Transformer
Ans. c
27. SMPS are classified into _______ types depending up its input / output.
a. 3
b. 2
c. 4
d. 6
Ans. c
28. SMPS with ac input and dc output is used as
a. Current converter
b. Frequency changer
c. Rectifier
d. cycle converter
Ans. c
29. SMPS with dc input and ac output is used as
a. Current converter
b. Frequency changer
c. Rectifier
d. Inverter
Ans. d
30. Linear power supplies use a transformer operating at the mains frequency of ______ Hz.
a. 50
b. 60
c. 50 or 60
d. none of these
Ans. C
31. SMPS use transformer operating at the frequency of ___________
a. 50 Hz to 1 kHz
b. 50 kHz to 1 kHz
c. 5 kHz to 1MHz
d. 50 kHz to 10MHz
Ans. b
32. The applied ac power to a half wave rectifier is 100W the ac output power obtained is 40W.the rectification efficiency is
a. 30%
b. 40%
c. 50%
d. 60%
Ans. b