Description : What type of insulator works well at very high frequencies?
Last Answer : A shorted quarter-wave section called a metallic insulator.
Description : What are the most common insulators used for extremely high voltages?
Last Answer : Varnished cambric and oil-impregnated paper.
Description : In applications where electronic waveforms are displayed on a CRT screen, the input signal is normally applied to what CRT element?
Last Answer : The vertical-deflection plate.
Description : What coordinates are displayed on an rhi scope?
Last Answer : Range and elevation.
Description : When an operating system prompt (A>) is displayed on the screen, what do you enter from the keyboard to load an application program?
Last Answer : The program name.
Description : On the CRT display, what information is displayed in Quadrant 4?
Last Answer : Positive voltage (+V) and negative current ( −I).
Description : What is the filter called that passes low frequencies but rejects or attenuates high frequencies?
Last Answer : Low-pass filter, high-frequency discriminator or high-frequency attenuator.
Description : How does transit time affect the relationship of the grid voltage and the plate current at high frequencies?
Last Answer : Transit time causes the grid voltage and plate current to be out of phase
Description : What is an advantage of using horizontal polarization at high frequencies?
Last Answer : Less interference is experienced by man-made noise sources
Description : What type of coupling is most effective at high frequencies?
Last Answer : Impedance coupling.
Description : Superconductors are those elements – (1) Whose conductivity is intermediate between metals and insulators (2) Whose resistance falls almost to zero at very low temperature (3) Which conduct electricity only at super-high temperature (4) Which conduct electricity only, at super-high temperatures
Last Answer : (2) Whose resistance falls almost to zero at very low temperature Explanation: Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in ... lines from the interior of the superconductor as it transitions into the superconducting state.
Description : Superconductors are those elements (1) Whose conductivity is intermediate between metals and insulators (2) Whose resistance falls almost to zero at very low temperatures (3) which turn into insulators at very low temperatures (4) which conduct electricity only at super-high temperatures
Last Answer : Whose resistance falls almost to zero at very low temperatures
Description : Choose the characteristics NOT displayed by the postmaster. (a) Empathetic and forgiving (b) Compassionate and placid (c) Argumentative and insolent (d) Polite and helpful
Last Answer : (c) Argumentative and insolent
Description : . Why are coaxial lines more efficient at microwave frequencies than two-wire transmission lines?
Last Answer : The electromagnetic fields are completely confined
Description : A cavity that vibrates at its natural frequency produces a louder sound than at other frequencies. What term is used to describe this phenomenon?
Last Answer : Resonance.
Description : What type filter is used to block the passage of current for a narrow band of frequencies, while allowing current to flow at all frequencies above or below this band?
Last Answer : . Band-reject.
Description : What type filter is used to allow a narrow band of frequencies to pass through a circuit and attenuate all other frequencies above or below the desired band?
Last Answer : Bandpass.
Description : What term is used to describe the frequency at which the filter circuit changes from the point of rejecting the unwanted frequencies to the point of passing the desired frequencies?
Last Answer : Frequency cutoff (fco).
Description : What is the filter called in which the low frequencies do not produce a useful voltage?
Last Answer : High-pass filter, low-frequency discriminator, or low-frequency attenuator.
Description : What is the device called that will separate alternating current from direct current, or that will separate alternating current of one frequency from other alternating currents of different frequencies?
Last Answer : A filter.
Description : What is the band of frequencies called that is included between the two points at which current falls to 70 percent of its maximum value in a resonant circuit?
Last Answer : Bandwidth of the circuit
Description : What effect does transit time have on a conventional triode operated at uhf frequencies?
Last Answer : It causes the control grid to short to the cathode
Description : How does fog affect radio waves at frequencies above 2 gigahertz?
Last Answer : It can cause attenuation by absorbtion.
Description : When a wide band of frequencies is transmitted simultaneously, each frequency will vary in the amount of fading. What is this variable fading called?
Last Answer : Selective fading.
Description : Receiver bandwidth is defined as those frequencies spread between what two points of the receiver response curve?
Last Answer : Half-power points.
Description : What IF frequencies are normally used in radar receivers
Last Answer : Thirty or sixty megahertz.
Description : What transmitter component allows the radiation of a large number of discrete frequencies over a wide band?
Last Answer : . Frequency synthesizer.
Description : Why do 2D air-search radars use relatively low carrier frequencies and low pulse-repetition rates?
Last Answer : Increased maximum range.
Description : Is it possible for a transmission line to operate improperly at certain frequencies and properly at others?
Last Answer : Yes, it is quite common.
Description : What device sweeps a band of frequencies to determine frequencies and amplitudes of each frequency component?
Last Answer : Spectrum analyzer.
Description : At frequencies above 100 megahertz, the intrinsic (i) region causes a pin diode to act as what?
Last Answer : Variable resistance.
Description : The cavities of a multicavity klystron are tuned to slightly different frequencies in what method of tuning?
Last Answer : Stagger tuning.
Description : When using frequencies above 30 megahertz, you are normally limited to using what range?
Last Answer : Line of sight.
Description : What frequencies are provided through the back-panel BNC?
Last Answer : 1 MHz and 10 MHz.
Description : What type of polarization should be used if an antenna is mounted on a moving vehicle at frequencies below 50 megahertz?
Last Answer : Vertical polarization.
Description : What type of polarization should be used at medium and low frequencies?
Description : What circuit section is required in the output of a multivibrator modulator to eliminate unwanted output frequencies?
Last Answer : An LCR filter.
Description : With a single modulating tone, what is the amplitude of the sideband frequencies at 100-percent modulation?
Last Answer : One-half the amplitude of the carrier.
Description : The metals occuring at the lower most position in the electromotive series (A) Do not resist corrosion (B) Resist corrosion very strongly (C) Are very brittle (D) Are heat insulators
Last Answer : (B) Resist corrosion very strongly
Description : In electronic circuits, what name is given to a frequency discriminating network designed to select or pass certain bands of frequencies with low attenuation and cause very high attenuation to other frequencies?
Last Answer : ANSWER: FILTER
Description : Which of the following statements is not true with respect to microwaves? (A) Electromagnetic waves with frequencies from 300 GHz to 400 THz. (B) Propagation is line-of-sight. (C) Very ... waves cannot penetrate walls. (D) Use of certain portions of the band requires permission from authorities.
Last Answer : (A) Electromagnetic waves with frequencies from 300 GHz to 400 THz.
Description : Enantiomers have which of the following characteristics? (a) rotate ordinary light (b) have the same melting point (c) are superimposable mirror images (d) react with optically active molecules at the same rate
Last Answer : have the same melting point
Description : The compounds used as gaseous insulators in high voltage generators is
Last Answer : The compounds used as gaseous insulators in high voltage generators is A. `SF_(4)` B. `SF_(6)` C. `SCl_(6)` D. `TeF_(6)`
Description : A bird sitting on a high tension electric wire does not get electrocuted because – (1) it has high resistance (2) the body is earthed (3) it does not form a closed path for the flow of current (4) its feet are good insulators
Last Answer : (3) it does not form a closed path for the flow of current Explanation: Electricity travels from a place of high voltage to low voltage, just as water travels from high elevation to low ... When electricity travels through a body in this fashion, electrocution takes place, and the bird can die.
Description : Dielectric constant will be high in a) Conductors b) Semiconductors c) Insulators d) Superconductors
Last Answer : c) Insulators
Description : High voltage transmission lines use (a) suspension insulators (b) pin insulators (c) both (a) and (b) (d) none of the above
Last Answer : (a) suspension insulators
Description : A bird sitting on a high tension electric wire does not get electrocuted because (1) it has high resistance (2) the body is earthed (3) it does not form a closed path for the flow of current (4) its feet are good insulators
Last Answer : it does not form a closed path for the flow of current
Description : What happens insulators when high voltage passes through transmission lines whether it breaks or lose it's insulating property?
Last Answer : I think it will breaks when it crosses breakdown voltage .
Description : At very low frequencies a series R-C circuit behaves as almost purely?
Last Answer : At very low frequencies a series R-C circuit behaves as almost purely capacitive.