Showing posts with label elex review series. Show all posts
Showing posts with label elex review series. Show all posts

Thursday, April 1, 2010

Electronics Review Series 3 (10 Questions)

1. How much power does an electronic equipment consume, assuming a 5.50-A current flowing and a 120-V power source?
Solution: P = EI = (120)(5.5)
Ans. 660-W

2. Which of the following characterizes CMOS logic?
bipolar FETs
P-channel FETs
N-channel FETs
both P-channel and N-channel FETs
Ans. both P-channel and N-channel FETs

3. What refers to the form of DC motor with common field coils for both motor and generator?
Ans. dynamotor

4. What device stays on once triggered and stores one of two conditions as a digital circuit?
Ans. latch

5. ___ is a user program that has the ability to move a robot axis to any position within its range.
Ans. point-to-point

6. Find the flux density in gauss having a flux of 20,000-Mx having a perpendicular area of 2-cm^2.
Solution: 20000/2
Ans. 10,000 gauss

7. A software that converts a high level language program into machine or assembly language program:
Ans. compiler

8. A SAW device has electrodes that are desbcribed as:
Ans. interdigital

9. What is the cause of parallax error in analog-type meter?
Ans. reading the meter at an angle

10. Which semiconductor material is commonly used in the construction of LEDs?
Ans. gallium arsenide

Electronics Review Series 2 (20 Questions)

1. The knee voltage of a diode is approximately equal to:
Ans. barrier potential

2. What do you call the flux that does not follow the intended path in a magnetic circuit?
Ans. leakage flux

3. The ratio between the primary and the secondary currents in a transformer does not depend on:
Ans. nature of the core

4. Which is NOT part of CRT of oscilloscope?
aquadag coating
deflection plate
digital panel meter
electron gun
Ans. digital panel meter

5. An amplifier with an input resistance of 600 ohms has an input current of 500 microamperes. It delivers 100 milliampere to a 1000 ohm load. Calculate the dB gain of the amplifier.
Solution: 10log(Pout/Pin) = 10log((1k*100m^2)/(600*500u^2))
Ans. 48.24-dB

6. How many silver-zinc cells in series are needed for a 9-V battery?
Ans. 6

7. Which meter uses a dual triode tube and requires external power for operation?
Ans. VTVM

8. What is the most available LED color?
Ans. red

9. What term is used for an energy stored in an electromagnetic or electrostatic field?
Ans. potential energy]

10. What is the reciprocal of capacitance?
Ans. elastance

11. What is th input voltage of a carbon zinc cell?
Ans. 1.5-V

12. How does a conductor behave at absolute zero temperature?
Ans. as a superconductor

13. The attraction or repulsion between two magnetic poles is directly proportional to their strengths:
Ans. Coulomb's First Law

14. A half adder can be constructed using a/an:
Ans. XOR and AND gates

15. What is a thin layer in a PCB which is bounded to an insulating base material?
Ans. substrate

16. A window comparator requires how many op-amps?
Ans. 2

17. What refers to the hardware data entry and entry points of a microcomputer?
Ans. ports

18. What term is used in electronic measuring devices when a metal increases resistance due to heat produced by current flowing through them?
Ans. positive temperature coefficient

19. What oscillator operates on the principle of velocity modulation and changing the speed of electron passing through the tube?
Ans. Klystron

20. Which of the following ICs contain the most gates?
LSI
MSI
SSI
VLSI
Ans. VLSI

Wednesday, March 31, 2010

Electronics Review Series 1 (41 Questions)

1. Distance between the rotor and ... is called:
Ans. slip

2. 25-uH and 10-pF in parallel, what is the frequency?
Solution: f = 1/(2pi(sqrt(LC))) = 1/(2pi(sqrt(25u*10p)))
Ans. 10.1-MHz

3. What is the main consideration in the output stage of amplifiers?
Ans. power gain

4. 100010010111 base 2 -> DEC
Ans. 897

5. As magnetic intensity decreases, relative permeability of a magnetic material:
Ans. increases

6. When an SCR is compared to a switch, it is considered as ___ switch:
Ans. unidirectional

7. A standalone solar power system uses:
Ans. solar power and battery

8. An input signal that can activate or disable a gate:
Ans. strobe

9. a temperature coefficient of resistance of electrolytes:
Ans. negative

10. A type of secondary cell that can be recharged but with an electrolyte that cannot be refilled:
Ans. sealed rechargeable cell

11. Which of the following is a paramagnetic material?
carbon
copper
bismuth
oxygen
Ans. oxygen

12. B2F base 16 -> octal
Ans. 5457

13. CMOS means
Ans. complementary metal-oxide semiconductor

14. Which VT can be used for high frequency amplification?
Ans. pentode

15. If F = xy + x'y', Boolean expression is said to be implemented using decoders and OR gates, the connection involves:
Ans. 2 to 4 line decoders with 1 OR gate

16. Refers to the magnetic lines of force:
Ans. flux

17. With PNP voltage divider bias, you must use:
Ans. negative power supplies

18. A good conductor has how many valence electrons?
Ans. 1

19. A technique used to eliminate the need for inductive elements in monolithic integrated circuits:
Ans. RC synthesis

20. A multi-stage amplifier uses at least how many transistors?
Ans. 2

21. Which of the following is a DC bridge that is very useful for making extremely accurate voltage measurements?
Wheatstone bridge
potentiometer bridge
Kelvin bridge
Owen bridge
Ans. potentiometer bridge

22. What is meant by interfacing in computer systems?
Ans. synchronization od digital information transmission in computer and I/O external device

23. Mass of proton or neutron is ___ times of an electron:
Ans. 1,836

24. Class of mass memory devices that uses a laser beam to write or read onto a specified coated disk:
Ans. optical disk memory

25. What is the total effective capacitance of two 0.25-uF capacitors connected in series?
Solution: 0.25^2 + 0.25^2
Ans. 0.125-uF

26, An open inductor has __ resistance and __ inductance:
Ans. infinite R and zero L

27. When the gas pressure in the gas-filled diode is increased, its PIV rating:
Ans. decreases

28. Which of the following has the lowest dielectric strength?
glass
paper
mica
teflon
Ans. paper

29. Approximate mass of neutron at rest:
Ans. 1.6726 x10^-27 grams

30. Given L = 3-uH; C = 40-pF; what is the frequency in series?
Solution: f = 1/(2pi(sqrt(3u*40p)))
Ans. 14.5-MHz

31. An inductive circuit of resistance 16.5 ohms and inductance of 0.14-H takes a current of 25-A. If the frequency is 50-Hz, find the supply voltage.
Solution: Z = sqrt(R^2 + (2pi(fL))^2)
Z = 46.9755 ohms
V = ZI = 46.9755(25)
Ans. 1174.39-V

32. What is the advantage of a pentode tube over a triode?
Ans. less control grid-to-plate capacitance

33. This occurs in PN diode when the electric field in the depletion layer increases to the point where it can break covalent bonds and generate electron hole pairs.
Ans. Zener breakdown

34. A vacuum tube will conduct only if its plate is ___ with respect to cathode.
Ans. positive (+)

35. An amplifier with 85% efficiency is likely to be:
Ans. class C

36. The pointer of an indicating instrument is generally made of:
Ans. aluminum

37. What will happen to an atom if an electron is either taken out or taken into the same atom?
Ans. becomes an ion

38. What is the next binary number following 10111 base 2 in the counting sequence?
Ans. 11000

39. The ratio between the active power and the apparent power of a load in an AC circuit is called:
Ans. power factor

40. Transmit time is the time taken by the electrons or holes to pass from:
Ans. emitter to collector

41. A resistor wound with a wire doubled back on itself to reduce the inductance is referred to as:
Ans. bifiliar resistor