# Define critical frequency as used in filters

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## Related questions

Explain why filters are used in signal conditioning.

In an isolated output dc-to-dc fly back converter, the high frequency transformer used works as an inductor (a) during turn -on period of the switching device (b) during turn off period of the switching device (c) during both (d) none of these

State types of filters. Define each of them.

Assertion (A) : Wein bridge oscillator is generally used as a variable audio frequency oscillator Reason (R) : by using either capacitor (or) resistor in one of the arms of the bridge, the frequency of a wein bridge oscillator can be varied (A) Both (A) & (R) are true & (R) is correct explanation of (A) (B) Both (A) & (R) are true but (R) is not the correct explanation of (R). (C) (A) is true but (R) is false (D) (A) is false but (R) is true

If the gain of the critical damped system is increased it will behave as?

Which is used to store critical pieces of data during subroutines and interrupts: (A) Stack (B) Queue (C) Accumulator (D) Data register

Poles which produce high Q factor in active RC filters are  A) On the negative real axis close to origin B) On the negative real axis away from origin C) Complex poles away from imaginary axis D) Complex poles near the imaginary axis

The S to Z domain transformation in digital filters which transforms imaginary axis to perimeter of unit circle with no aliasing error is  A) Backward difference integration B) Forward difference integration C) Impulse invariant transformation D) Bilinear integration

Cut-off frequency in a resonating circuit is also called as : (A) Full power frequency (B) Half power frequency (C) Resonant frequency (D) Corner frequency

The Ku frequency band used in satellite communication (for uplink and downlink) is: (1) 14 GHz and 11 GHz (2) 30 GHz and 20 GHz (3) 70 GHz and 50 GHz (4) 60 GHz and 45 GHz

Frequency shift keying is used mostly in: (1) Telegraphy (2) Telephony (3) Satellite communication (4) Radio transmission

Weins bridge is used for measurement of frequency in the applied voltage waveform is measurement of frequency in the applied voltage waveform is   (A)sinusoidal (B) square (C) rectangular (D) triangular

In satellite communication, frequency modulation is used because satellite channel has  a. High modulation index  b. Small bandwidth and negligible noise  c. Large bandwidth and severe noise   d. Maximum bandwidth and minimum noise

Define : i) Amplitude ii) Frequency iii) Time period iv) Angular velocity related to a.c.

Define : (i)Threshold frequency (ii)Work function

Define: 1) frequency, 2) cycle, 3) time period, 4) amplitude

In a dc shunt generator critical field circuit resistance line is the line drawn (A) above the OCC (B) below the OCC (C) tangent to the saturation curve (D) tangent to the linear portion of OCC

The critical clearing time of a fault in power system is related to   (a) Reactive power limit (b) Steady state stability limit (c) Short-circuit current limit (d) Transient stability limit

In a superconductor, if the temperature is decreased below its critical temperature, the value of critical magnetic field will (a) Increase (b) Decrease (c) Not change (d) Increase or decrease depending on the superconductor material

In a superconductor the value of critical density depends upon?

Synchros in control systems are used as (a) error detectors (b) encoders (c) both (a) and (b) (d) none of these

A bipolar junction transistor (BJT) is used as a power control switch by biasing it in the cut-off region (OFF state) or in the saturation region (ON state). In the ON state, for the BJT  (A) both the base-emitter and base-collector junctions are reverse biased (B) the base-emitter junction is reverse ... (C) the base-emitter junction is forward biased, and the base-collector junction is reverse biased (D) both the base-emitter and base-collector junctions are forward biased

Which of the following elements are used as dopants in silicon or germanium semiconductors? A) Antimony B) Phosphorus C) Arsenic D) All the above

Which of the following is used in a circuit breaker as the medium in which the arc forms? A) Insulating gas B) Insulating oil C) Vacuum D) All the above

In moving iron instruments, eddy current damping cannot be used as  (a) They have a strong operating magnetic, field (b) They are not normally used in vertical position (c) They need a large damping force, which can only be provided by air friction (d) The introduction of a permanent magnet required for eddy current damping would distort the existing weak operating magnetic field

SiN is used in semiconductor industry such as a diffusion mask during device processing, a dielectric for memory devices because it offers a (a) High breakdown field strength and a low fixed interface charge density. (b) Low breakdown field strength and a high fixed interface charge density. (c) High breakdown field strength and a high fixed interface charge density. (d) Low breakdown field strength and a low fixed interface charge density.

In an electronic ohmmeter an op -amp is used as a: -  a) sommer b) multiplier c) buffer amplifier d) integrator

In pneumatic control systems the control valve used as final control element converts

Define the following terms as referred to battery. a) E.M.F b) Internal resistance c) Ah efficiency d) WAh efficiency

For Butterworth & Chebyshev filters, the correct statement is : a. Butterworth response has a sharp cut-off b. Chebyshev response has a flat response in the pass band c. Butterworth response has ripples -in the pass band d. Chebyshev response has ripples in the pass band

Active High pass filters consist : -  a) RC circuits b) Differential amplifiers c) Operational amplifiers d) RLC circuits

Filters with the ___ characteristic are useful when a rapid roll-off is required because it provides a roll-off rate greater than –20/dB/decade/pole:  (1) Butterworth (2) Chebyshev (3) Bessel (4) Elliptical

For a 500 Hz frequency excitation, a 50 km long power line will be modeled as

As the wave frequency approaches to cut-off frequency of wave guide, the correct statement is : a. The phase velocity of waves tends to zero. b. The phase velocity of waves tends to velocity of light. c. The phase velocity of waves tends to infinite. d. None of these.

A chopper operating at a fixed frequency is feeding an R-L load. As they duty ratio of the chopper is increased from 25% to 75%, the ripple in the load current.

Which of the following thyristors can be used for high frequency of operation? A) TRIAC B) DIAC C) SCR D) GTO

Which of the following oscillators is used for generation of high frequency signal ? (a) RC phase shift oscillator (b) Blocking oscillator (c) Wein bridge oscillator (d) L-C oscillator

Thermocouple instruments can be used for a frequency range upto   (a) 100Hz (b) 5000 Hz (c) 1 MHz (d) 50 MHz and above

For measurement of radio frequency ac signals __________ type meter is used