Description : In a 2-mass 3 spring vibrating system the two masses each are of 9.8 kg coupling spring is having a stiffness of 3430 N/m whereas the other two springs have each a stiffness of 8820 N/m. The two natural frequencies in rad /sec are A) 10 & 20 B) 20 & 30 C) 30 & 40D) 40 & 50
Last Answer : C) 30 & 40
Description : What type of insulator works well at very high frequencies?
Last Answer : A shorted quarter-wave section called a metallic insulator.
Description : At very high frequencies, what characteristics are displayed by ordinary insulators?
Last Answer : The characteristics of the dielectric of a capacitor.
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 are two advantages of this type of coupling?
Last Answer : It uses fewer components than capacitive coupling and can provide an increase in gain.
Description : If current gain is required from an rf amplifier, what type of component should be used as an output coupling element?
Last Answer : A step-down transformer.
Description : What type coupling would be most useful for an audio amplifier between the first and second stages?
Last Answer : RC coupling.
Description : What type coupling is usually used to couple the output from a power amplifier?
Last Answer : Transformer coupling.
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 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 : Loose or inefficient coupling of energy into or out of a waveguide can be accomplished by the use of what method?
Last Answer : Slots and apertures.
Description : What is the most common form of coupling for an rf amplifier?
Description : What effect does flux leakage in a transformer have on the coefficient of coupling (K) in the transformer?
Last Answer : it causes K to be less than unity (I).
Description : Is coupling loss from angular misalignment more critical in expanded beam or butt-jointed connectors?
Last Answer : Expanded beam connectors.
Description : Is coupling loss from fiber separation and lateral misalignment more critical in expanded-beam or butt-jointed connectors?
Last Answer : Butt-jointed connectors.
Description : What are the two methods used for feedback coupling?
Last Answer : Inductive and capacitive.
Description : Does coupling loss from refractive index profile difference result when the receiving fiber has a larger profile parameter
Last Answer : Fiber alignment.
Description : What is the basic fiber cleaving technique for preparing optical fibers for coupling?
Last Answer : Score-and-break.
Description : How does index matching gel affect the amount of coupling loss caused by (a) fiber separation, (b) lateral misalignment, and (c) angular misalignment?
Last Answer : (a) Reduces coupling loss, (b) does not change coupling loss, and (c) increases coupling loss
Description : What connection properties result in fiber optic connector coupling loss?
Last Answer : Poor fiber alignment and end preparation, fiber mismatches, and Fresnel reflection.
Description : In fiber-to-fiber connections, Fresnel reflection is one source of coupling losses. Light is reflected back into the source fiber and is lost. What causes Fresnel reflection?
Last Answer : A step change in refractive index that occurs at fiber joints, caused by fiber separation.
Description : Fiber-to-fiber coupling loss is affected by intrinsic and extrinsic coupling losses. Can intrinsic coupling losses be limited by limiting fiber mismatches?
Last Answer : Yes.
Description : What are the main causes of coupling loss?
Last Answer : Poor fiber end preparation and poor fiber alignment.
Description : How are source-to-fiber coupling and microbending and macrobending losses affected by changes in core diameter and D?
Last Answer : Coupling efficiency increases with both core diameter and D, while bending losses increase directly with core diameter and inversely with D.
Description : In a circuit using grid-leak biasing, the coupling capacitor (Cc) chargcharge path?
Last Answer : rkg, the cathode to grid resistance.
Description : What is meant by the coefficient of coupling?
Last Answer : The ratio of the fines of force produced by one coil to the lines of force that link another coil. It is never greater than one.
Description : Will fiber coupling loss generally increase or decrease if the mode field diameter of a single mode fiber is decreased?
Last Answer : Increase.
Description : As the core and cladding modes travel along the fiber, mode coupling occurs. What is mode coupling?
Last Answer : Mode coupling is the exchange of power between two modes.
Description : . What is the most common form of coupling?
Description : What are four methods of coupling amplifier stages?
Last Answer : Direct, RC, impedance, and transformer coupling.
Description : What is the purpose of an amplifier-coupling network?
Last Answer : To transfer energy (a signal) from one stage to another.
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 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.