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
Wednesday, March 31, 2010
Communications Review Series 2
1. Known as the Philippine Public Telecomm Act
Ans. RA # 7925
2. Low-speed modems generally have bit rates of:
Ans. 2400 bps
3. Direct satellite based allocation:
Ans. 12.2- to 12.7-GHz downlink / 17.3- to 17.8 GHz uplink
4. Operating frequency of LORAN C:
Ans. LF band
5. Important requirement for successful transmission system using light:
Ans. powerful, reliable light source
6. Free space attenuation of satellite comm system operating at 36,000-km above Earth at 5-GHz:
Solution: 92.4 + 20log(36000) + 20log(5)
Ans. 197.51-dB
7. Approximate path loss from satellite-to-Earth station:
Ans. 200-dB
8. Stacking antenna elements are used to:
Ans. increase sensitivity to weak signals
9. Transmission line: 40-nF/ft and 0.5-mH/ft, Zo = ?
Solution: Zo = sqrt(L/C) = sqrt(0.5m/40n)
Ans. 111.80 ohms
10. Judgment on the case against an ECE will become final and executory after ___ days.
Ans. 30
11. The number of scanning lines is __ per second.
Ans. 15750
12. The maximum intelligibility for voice frequency is located between:
Ans. 1000- to 3000-Hz
13. What is multiplexing?
Ans. more than one data source over one cable line
14. Which ionosphere has an average of 225-km height at night?
Ans. F2 layer
15. Which wire color is used to transmit the signal?
Ans. green
16. The main advantage of SSB over standard AM or DSB:
Ans. less spectrum space is used
17. The function which tends to maintain the sound volume level of a voice receiver nearly constant for a large signal strength range:
Ans. AGC (automatic gain control)
18. Which of the following transmits only one sideband?
H3E; C3F; A3E; B8E
Ans. H3E
19. The AGC voltage of a radio receiver is always:
Ans. DC but may have polarity
20. A balanced modulator used to demodulate an SSB signal is called:
Ans. product detector
21. The Ultimate Dolby Surround System is the:
Ans. Dolby Prologic
22. A coupler which consists of a series of lenses and a partly reflective surface:
Ans. beam-splitting coupler
23. One neper is how many decibels?
Ans. 8.686
24. Light enters a glass plate whose index of refraction is 1.6 at an angle of incidence of 30 degrees. The angle of refraction is:
Solution: sin^-1(sin30/1.6)
Ans. 18 degrees
25. What is a trunk?
Ans. a telephone line connecting two central offices
26. The values of Vmax and Vmin read from an AM wave on an oscilloscope are 2.8 and 0.3 respectively. The percentage of modulation is:
Solution: (2.8-0.3)/(2.8+0.3)
Ans. 80.65%
27. The ratio of the peak modulating signal to the peak carrier voltage is referred to as:
Ans. modulation index
28. The time deviation for 1 horizontal trace:
Ans. 52 microseconds
29. In SSB, voice compression is better in the AF or RF section?
Ans. RF
30. A term applied to third and higher order products, which can greatly degrade the performance of a system:
Ans. composite triple beat
31. The number of vibration or pressure fluctuations per second:
Ans. frequency
32. If the instantaneous RF potentials on the two sides of a magnetron cavity are of opposite polarities, the operation is in the:
Ans. pi-mode
33. The circuit that recovers the original modulating signal (information) from an AM signal is known as a:
Ans. demodulator
34. The free space attenuation between 2 microwave antennas 40-km apart at 8-GHz:
Solution: 92.4 + 20log(40) + 20log(8)
Ans. 142.50-dB
35. For an I = 0.4, and Q = 0.7, find the value of the chrominance signal voltage:
Ans. 0.8-V
36. When did the first transatlantic radio communications take place?
Ans. 1901
37. What is the polarization of a discone antenna?
Ans. vertical
38. The ratio of the speed of light in a vacuum and the speed of light in the material used:
Ans. refractive index
39. The maximum transmitter power of a television broadcast translator station operated by TV broadcast licenses:
Ans. 1-kW
40. Noise that occurs via capacitive or inductive coupling in a cable:
Ans. crosstalk
41. In pulse radar set, the function of the diplexer is to:
Ans. allow the transmitter and the receiver to operate from a common antenna
Ans. RA # 7925
2. Low-speed modems generally have bit rates of:
Ans. 2400 bps
3. Direct satellite based allocation:
Ans. 12.2- to 12.7-GHz downlink / 17.3- to 17.8 GHz uplink
4. Operating frequency of LORAN C:
Ans. LF band
5. Important requirement for successful transmission system using light:
Ans. powerful, reliable light source
6. Free space attenuation of satellite comm system operating at 36,000-km above Earth at 5-GHz:
Solution: 92.4 + 20log(36000) + 20log(5)
Ans. 197.51-dB
7. Approximate path loss from satellite-to-Earth station:
Ans. 200-dB
8. Stacking antenna elements are used to:
Ans. increase sensitivity to weak signals
9. Transmission line: 40-nF/ft and 0.5-mH/ft, Zo = ?
Solution: Zo = sqrt(L/C) = sqrt(0.5m/40n)
Ans. 111.80 ohms
10. Judgment on the case against an ECE will become final and executory after ___ days.
Ans. 30
11. The number of scanning lines is __ per second.
Ans. 15750
12. The maximum intelligibility for voice frequency is located between:
Ans. 1000- to 3000-Hz
13. What is multiplexing?
Ans. more than one data source over one cable line
14. Which ionosphere has an average of 225-km height at night?
Ans. F2 layer
15. Which wire color is used to transmit the signal?
Ans. green
16. The main advantage of SSB over standard AM or DSB:
Ans. less spectrum space is used
17. The function which tends to maintain the sound volume level of a voice receiver nearly constant for a large signal strength range:
Ans. AGC (automatic gain control)
18. Which of the following transmits only one sideband?
H3E; C3F; A3E; B8E
Ans. H3E
19. The AGC voltage of a radio receiver is always:
Ans. DC but may have polarity
20. A balanced modulator used to demodulate an SSB signal is called:
Ans. product detector
21. The Ultimate Dolby Surround System is the:
Ans. Dolby Prologic
22. A coupler which consists of a series of lenses and a partly reflective surface:
Ans. beam-splitting coupler
23. One neper is how many decibels?
Ans. 8.686
24. Light enters a glass plate whose index of refraction is 1.6 at an angle of incidence of 30 degrees. The angle of refraction is:
Solution: sin^-1(sin30/1.6)
Ans. 18 degrees
25. What is a trunk?
Ans. a telephone line connecting two central offices
26. The values of Vmax and Vmin read from an AM wave on an oscilloscope are 2.8 and 0.3 respectively. The percentage of modulation is:
Solution: (2.8-0.3)/(2.8+0.3)
Ans. 80.65%
27. The ratio of the peak modulating signal to the peak carrier voltage is referred to as:
Ans. modulation index
28. The time deviation for 1 horizontal trace:
Ans. 52 microseconds
29. In SSB, voice compression is better in the AF or RF section?
Ans. RF
30. A term applied to third and higher order products, which can greatly degrade the performance of a system:
Ans. composite triple beat
31. The number of vibration or pressure fluctuations per second:
Ans. frequency
32. If the instantaneous RF potentials on the two sides of a magnetron cavity are of opposite polarities, the operation is in the:
Ans. pi-mode
33. The circuit that recovers the original modulating signal (information) from an AM signal is known as a:
Ans. demodulator
34. The free space attenuation between 2 microwave antennas 40-km apart at 8-GHz:
Solution: 92.4 + 20log(40) + 20log(8)
Ans. 142.50-dB
35. For an I = 0.4, and Q = 0.7, find the value of the chrominance signal voltage:
Ans. 0.8-V
36. When did the first transatlantic radio communications take place?
Ans. 1901
37. What is the polarization of a discone antenna?
Ans. vertical
38. The ratio of the speed of light in a vacuum and the speed of light in the material used:
Ans. refractive index
39. The maximum transmitter power of a television broadcast translator station operated by TV broadcast licenses:
Ans. 1-kW
40. Noise that occurs via capacitive or inductive coupling in a cable:
Ans. crosstalk
41. In pulse radar set, the function of the diplexer is to:
Ans. allow the transmitter and the receiver to operate from a common antenna
DC Metering
A "movement" is the display mechanism of a meter.
D'arsonval and Weston - common polarity-sensitive meter designs, PMMC (permanent magnet moving coil) meter movement
Galvanometer - The first meter movements built.
Electrostatic meter movement - used for
measuring ver high voltage because of high resistance.
CRT - uses polarity-sensitive meters, because of deflection and reversal of electrons at either positive or negative side of the tube
CRT contains two pairs of deflection plates rather than just one
------------
FULL SCALE INDICATION:
In electromagnetic movements - "full-scale deflection current" is necessary to rotate the needle so that it points to the exact end of the indicating scale.
In electrostatic movements - the full-scale rating will be expressed as the value of voltage resulting in the maximum deflection of the needle actuated by the plates, or the value of voltage in a cathode-ray tube which deflects the electron beam to the edge of the indicating screen.
In digital movements - it is the amount of voltage resulting in a "full-count" indication on the numerical display: when the digits cannot display a larger quantity.
------------
Electromagnetic movements work on the principle of a magnetic field being generated by electric current through a wire. Examples of electromagnetic meter movements include the D'Arsonval, Weston, and iron-vane designs.
Electrostatic movements work on the principle of physical force generated by an electric field between two plates.
Cathode Ray Tubes (CRT's) use an electrostatic field to bend the path of an electron beam, providing indication of the beam's position by light created when the beam strikes the end of the glass tube.
------------
Part 2
Extended voltmeter ranges are created for sensitive meter movements by adding series "multiplier" resistors to the movement circuit, providing a precise voltage division ratio.
------------
Part 3 VOLTMETER
Loading effect - present to some degree in every instance of voltmeter usage
Potentiometric or null-balance instrument - a final solution to voltmeter loading;
uses null detector or potentiometer to compare voltages
Null detector - a very sensitive device that can detect very small changes in voltage
Part 4 AMMETER
Hall-effect sensor - small magnetic field detector used in modern designs of clamp-on ammters to accurately determine field strength.
Part 5 OHMMETER
Requirements:
*Internal source of voltage - to create the necessary current to operate the movement
*Appropriate ranging resistors - to allow just the right amount of current through the movement at any given resistance
Ohmmeters only function correctly when measuring resistance that is not being powered by a voltage or current source.
The ohmmeter's accurate indication depends on the only source of voltage being its internal battery.
D'arsonval and Weston - common polarity-sensitive meter designs, PMMC (permanent magnet moving coil) meter movement
Galvanometer - The first meter movements built.
Electrostatic meter movement - used for
measuring ver high voltage because of high resistance.
CRT - uses polarity-sensitive meters, because of deflection and reversal of electrons at either positive or negative side of the tube
CRT contains two pairs of deflection plates rather than just one
------------
FULL SCALE INDICATION:
In electromagnetic movements - "full-scale deflection current" is necessary to rotate the needle so that it points to the exact end of the indicating scale.
In electrostatic movements - the full-scale rating will be expressed as the value of voltage resulting in the maximum deflection of the needle actuated by the plates, or the value of voltage in a cathode-ray tube which deflects the electron beam to the edge of the indicating screen.
In digital movements - it is the amount of voltage resulting in a "full-count" indication on the numerical display: when the digits cannot display a larger quantity.
------------
Electromagnetic movements work on the principle of a magnetic field being generated by electric current through a wire. Examples of electromagnetic meter movements include the D'Arsonval, Weston, and iron-vane designs.
Electrostatic movements work on the principle of physical force generated by an electric field between two plates.
Cathode Ray Tubes (CRT's) use an electrostatic field to bend the path of an electron beam, providing indication of the beam's position by light created when the beam strikes the end of the glass tube.
------------
Part 2
Extended voltmeter ranges are created for sensitive meter movements by adding series "multiplier" resistors to the movement circuit, providing a precise voltage division ratio.
------------
Part 3 VOLTMETER
Loading effect - present to some degree in every instance of voltmeter usage
Potentiometric or null-balance instrument - a final solution to voltmeter loading;
uses null detector or potentiometer to compare voltages
Null detector - a very sensitive device that can detect very small changes in voltage
- An ideal voltmeter has infinite resistance.
- Too low of an internal resistance in a voltmeter will adversely affect the circuit being measured.
- Vacuum tube voltmeters (VTVM's), transistor voltmeters, and potentiometric circuits are all means of minimizing the load placed on a measured circuit. Of these methods, the potentiometric ("null-balance") technique is the only one capable of placing zero load on the circuit.
- A null detector is a device built for maximum sensitivity to small voltages or currents. It is used in potentiometric voltmeter circuits to indicate the absence of voltage between two points, thus indicating a condition of balance between an adjustable voltage source and the voltage being measured.
Part 4 AMMETER
- Ammeter ranges are created by adding parallel "shunt" resistors to the movement circuit, providing a precise current division.
- Shunt resistors may have high power dissipations, so be careful when choosing parts for such meters!
- Shunt resistors can be used in conjunction with high-resistance voltmeters as well as low-resistance ammeter movements, producing accurate voltage drops for given amounts of current. Shunt resistors should be selected for as low a resistance value as possible to minimize their impact upon the circuit under test.
Hall-effect sensor - small magnetic field detector used in modern designs of clamp-on ammters to accurately determine field strength.
- An ideal ammeter has zero resistance.
- A "clamp-on" ammeter measures current through a wire by measuring the strength of the magnetic field around it rather than by becoming part of the circuit, making it an ideal ammeter.
- Clamp-on meters make for quick and safe current measurements, because there is no conductive contact between the meter and the circuit.
Part 5 OHMMETER
Requirements:
*Internal source of voltage - to create the necessary current to operate the movement
*Appropriate ranging resistors - to allow just the right amount of current through the movement at any given resistance
Ohmmeters only function correctly when measuring resistance that is not being powered by a voltage or current source.
The ohmmeter's accurate indication depends on the only source of voltage being its internal battery.
- Ohmmeters contain internal sources of voltage to supply power in taking resistance measurements.
- An analog ohmmeter scale is "backwards" from that of a voltmeter or ammeter, the movement needle reading zero resistance at full-scale and infinite resistance at rest.
- Analog ohmmeters also have nonlinear scales, "expanded" at the low end of the scale and "compressed" at the high end to be able to span from zero to infinite resistance.
- Analog ohmmeters are not precision instruments.
- Ohmmeters should never be connected to an energized circuit (that is, a circuit with its own source of voltage). Any voltage applied to the test leads of an ohmmeter will invalidate its reading.
ECE Laws 1
RA # 9292 - Electronics Engineering Law of 2004 - Submitted Feb. 2, 2004l; Approved April 17, 2004
RA # 5734 - ECE Law of the Philippines
June 21, 1969
EO # 125 - Reorganization Act of MOTC; Jan. 30, 2987
EO # 125-A - Creation of DOTC - April 13, 1987
DO # 11 - General rules and regulations governing the construction, installation, establishment, or operation, and possession or ownership, construction or manufacture, purchase, sale, or transfer of transmitters and transceivers in the Philippines; Jul 23, 1979
EO # 205 - CATV; June 30, 1987
DO # 5, s. 1948 - Commercial Radio operators; 3 yrs effectivity, renewable 30 days before expiration; 18 yrs old and above
EO # 255, s. 1987 - playing of 4 Filipino music every clock hour
EO # 436, s. 1997 - policy and guidelines CATV; Sept. 9, 1997
PD # 1987 - creation of VRB
EO # 546 - abolished the TCB and BOC which primary functions were to create NTC; Jul 23, 1979;
Act # 3846 - Radio control law of the Philippines; Nov. 11, 1931
Act # 3396 - Ship radio station law; Dec 5, 1927
RA #8370 - Children's TV law; Oct. 28, 1997
NTC MC # 6-2-81 - Non-commercial radio stations exempted from franchise
NTC MC # 14-89 - government radio operator certificate; Aug. 15, 1989
RA # 8792 - E-commerce act; June 14, 2000
EO # 266 - continuing professional education; Jul. 25, 1995
DO # 88 - Rules and regulations requiring the service of a duly registered ECE in Planning and Designing of radio stations, Installation or construction of radio stations, operation and maintenance of radio stations, manufacture and/or modification of radio communications equipment; Dec 28, 1973
Commonwealth Act # 146 - Public service law
DO # 7 - Rules and regulations governing the radio training schools in the Philippines
RA # 5734 - ECE Law of the Philippines
June 21, 1969
EO # 125 - Reorganization Act of MOTC; Jan. 30, 2987
EO # 125-A - Creation of DOTC - April 13, 1987
DO # 11 - General rules and regulations governing the construction, installation, establishment, or operation, and possession or ownership, construction or manufacture, purchase, sale, or transfer of transmitters and transceivers in the Philippines; Jul 23, 1979
EO # 205 - CATV; June 30, 1987
DO # 5, s. 1948 - Commercial Radio operators; 3 yrs effectivity, renewable 30 days before expiration; 18 yrs old and above
EO # 255, s. 1987 - playing of 4 Filipino music every clock hour
EO # 436, s. 1997 - policy and guidelines CATV; Sept. 9, 1997
PD # 1987 - creation of VRB
EO # 546 - abolished the TCB and BOC which primary functions were to create NTC; Jul 23, 1979;
Act # 3846 - Radio control law of the Philippines; Nov. 11, 1931
Act # 3396 - Ship radio station law; Dec 5, 1927
RA #8370 - Children's TV law; Oct. 28, 1997
NTC MC # 6-2-81 - Non-commercial radio stations exempted from franchise
NTC MC # 14-89 - government radio operator certificate; Aug. 15, 1989
RA # 8792 - E-commerce act; June 14, 2000
EO # 266 - continuing professional education; Jul. 25, 1995
DO # 88 - Rules and regulations requiring the service of a duly registered ECE in Planning and Designing of radio stations, Installation or construction of radio stations, operation and maintenance of radio stations, manufacture and/or modification of radio communications equipment; Dec 28, 1973
Commonwealth Act # 146 - Public service law
DO # 7 - Rules and regulations governing the radio training schools in the Philippines
Coaching Notes Comms 1
harmonics - causes distortion
Marconi - wireless telegraph
lambda/4 am broadcast antenna - 24 radials or more
industrial noise frequency - 15 - 160 MHz
For 100% percent modulation in AM, the modulation envelope has a peak value double the unmodulated carrier level.
The color phasor has what phase for the I signal? - 57deg
(Nov 1996)Multiplexing in a time division multiplexer occurs based upon - the positioning of data within a frame
The signal which is superimposed on a high-frequency sine wave is called - information
A duplexer is used to - Connect a receiver and a transmitter to the same antenna
(Nov 1998) What connects the front-end circuit of a VHF TV super heterodyne receiver? - Local oscillator, mixer and RF amplifier
pitch - determined by the frequency
AFC - holds the horizontal oscillator on frequency
fundamental frequency - lowest frequency produced by musical instruments
stability - major requirement of oscillators used in SSB receiver
Mel - unit of pitch
This noise increases with bias current level and is inversely proportional to the square of frequency. - burst noise
COMPARE - shot, flicker, thermal
ISB - commonly used in Telephone and Telegraph comm
above 20kHz - referred to as Radio freq
Baffle - A relatively rigid extended surface surrounding an acoustic source.
To what feature of the modulating tone is FM deviation proportional? - amplitude
What is gained by operating an oscillator on some subharmonic of the transmission frequency? - frequency stability
(Mar 1996) What is the primary advantage of DSBSC in AM? - No transmitter power is wasted in the carrier
Most household radio receiver uses ___ detector. - envelope
Q and I amplitudes - determine the purity of received colors
The audio is reconstructed from the radio wave by - the action of the filter capacitor connected across headset
(Apr 1998) An instrument for recording waveforms of audio frequency. - phonoscope
Marconi - wireless telegraph
lambda/4 am broadcast antenna - 24 radials or more
industrial noise frequency - 15 - 160 MHz
For 100% percent modulation in AM, the modulation envelope has a peak value double the unmodulated carrier level.
The color phasor has what phase for the I signal? - 57deg
(Nov 1996)Multiplexing in a time division multiplexer occurs based upon - the positioning of data within a frame
The signal which is superimposed on a high-frequency sine wave is called - information
A duplexer is used to - Connect a receiver and a transmitter to the same antenna
(Nov 1998) What connects the front-end circuit of a VHF TV super heterodyne receiver? - Local oscillator, mixer and RF amplifier
pitch - determined by the frequency
AFC - holds the horizontal oscillator on frequency
fundamental frequency - lowest frequency produced by musical instruments
stability - major requirement of oscillators used in SSB receiver
Mel - unit of pitch
This noise increases with bias current level and is inversely proportional to the square of frequency. - burst noise
COMPARE - shot, flicker, thermal
ISB - commonly used in Telephone and Telegraph comm
above 20kHz - referred to as Radio freq
Baffle - A relatively rigid extended surface surrounding an acoustic source.
To what feature of the modulating tone is FM deviation proportional? - amplitude
What is gained by operating an oscillator on some subharmonic of the transmission frequency? - frequency stability
(Mar 1996) What is the primary advantage of DSBSC in AM? - No transmitter power is wasted in the carrier
Most household radio receiver uses ___ detector. - envelope
Q and I amplitudes - determine the purity of received colors
The audio is reconstructed from the radio wave by - the action of the filter capacitor connected across headset
(Apr 1998) An instrument for recording waveforms of audio frequency. - phonoscope
Potentiometer
POTENTIOMETER
wiper - potentionmeter movable element
voltage divider - used in electric meter circuits
potentiometer - uses VDB
slidewire - the resistive strip of material in potentiometer
2 types:
linear
rotary
potentiometer division ratio - a function of resistance, and not the voltage applied
POTENTIAL (voltage) meter (control)
wiper - potentionmeter movable element
voltage divider - used in electric meter circuits
potentiometer - uses VDB
slidewire - the resistive strip of material in potentiometer
2 types:
linear
rotary
potentiometer division ratio - a function of resistance, and not the voltage applied
POTENTIAL (voltage) meter (control)
Gibilisco Quiz 1
1. The atomic number of an element is determined by:
A. The number of neutrons.
B. The number of protons.
C. The number of neutrons plus the number of protons.
D. The number of electrons.
2. The atomic weight of an element is approximately determined by:
A. The number of neutrons.
B. The number of protons.
C. The number of neutrons plus the number of protons.
D. The number of electrons.
3. Suppose there is an atom of oxygen, containing eight protons and eight
neutrons in the nucleus, and two neutrons are added to the nucleus. The resulting
atomic weight is about:
A. 8.
B. 10.
C. 16.
D. 18.
4. An ion:
A. Is electrically neutral.
B. Has positive electric charge.
C. Has negative electric charge.
D. Might have either a positive or negative charge.
5. An isotope:
A. Is electrically neutral.
B. Has positive electric charge.
C. Has negative electric charge.
D. Might have either a positive or negative charge.
6. A molecule:
A. Might consist of just a single atom of an element.
B. Must always contain two or more elements.
C. Always has two or more atoms.
D. Is always electrically charged.
7. In a compound:
A. There can be just a single atom of an element.
B. There must always be two or more elements.
C. The atoms are mixed in with each other but not joined.
D. There is always a shortage of electrons.
8. An electrical insulator can be made a conductor:
A. By heating.
B. By cooling.
C. By ionizing.
D. By oxidizing.
9. Of the following substances, the worst conductor is:
A. Air.
B. Copper.
C. Iron.
D. Salt water.
10. Of the following substances, the best conductor is:
A. Air.
B. Copper.
C. Iron.
D. Salt water.
11. Movement of holes in a semiconductor:
A. Is like a flow of electrons in the same direction.
B. Is possible only if the current is high enough.
C. Results in a certain amount of electric current.
D. Causes the material to stop conducting.
12. If a material has low resistance:
A. It is a good conductor.
B. It is a poor conductor.
C. The current flows mainly in the form of holes.
D. Current can flow only in one direction.
13. A coulomb:
A. Represents a current of one ampere.
B. Flows through a 100-watt light bulb.
C. Is one ampere per second.
D. Is an extremely large number of charge carriers.
14. A stroke of lightning:
A. Is caused by a movement of holes in an insulator.
B. Has a very low current.
C. Is a discharge of static electricity.
D. Builds up between clouds.
15. The volt is the standard unit of:
A. Current.
B. Charge.
C. Electromotive force.
D. Resistance.
16. If an EMF of one volt is placed across a resistance of two ohms, then the
current is:
A. Half an ampere.
B. One ampere.
C. Two amperes.
D. One ohm.
17. A backwards-working electric motor is best described as:
A. An inefficient, energy-wasting device.
B. A motor with the voltage connected the wrong way.
C. An electric generator.
D. A magnetic-field generator.
18. In some batteries, chemical energy can be replenished by:
A. Connecting it to a light bulb.
B. Charging it.
C. Discharging it.
D. No means known; when a battery is dead, you have to throw it away.
19. A changing magnetic field:
A. Produces an electric current in an insulator.
B. Magnetizes the earth.
C. Produces a fluctuating electric field.
D. Results from a steady electric current.
20. Light is converted into electricity:
A. In a dry cell.
B. In a wet cell.
C. In an incandescent bulb.
D. In a photovoltaic cell.
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