Electrical Engineering Relays and Sources Quiz

Electrical Engineering

• Δ2 V = - P / E is called Poisson equation.
• Concept of sending/receiving text etc. on computer networks is Email.
• Drawback of IIR (Infinite impulse response) filters is Instability.
• Full wave rectification needs minimum number of diodes: 2.
• A circuit of zero lagging power factor behaves as An inductive circuit.
• To improve the power factor, a Shunt capacitor should be connected to the power system.
• When the air gap field between rotor and stator increases, the power factor of the machine Decreases.
• The power factor of an ac circuit is equal to: Cosine of the phase angle.
• In an ac circuit, I x sin (Phi) is called the Wattless component of the current.
• According to free electron theory, in metals, electrons revolve because of Constant V.

Power Systems

• The power factor of an induction motor Decreases when the air gap field between rotor and stator increases.
• To improve the power factor, a Shunt capacitor should be connected to the power system.

Electronics

• Frequency shift keying is used mostly in Telegraphy.
• LVDT (linear variable differential transformer) is an Electromechanical device.
• The autocorrelation function is an even function.
• Probability density function of thermal noise is Gaussian.
• If 360 coulomb charge is stored for a time period of 30 minutes, the current will be 200mA.
• The potential difference between two similar charges is Nil.
• In Force-voltage analogy, Mass is analogous to Inductance.
• Top loading is sometimes used with an antenna in order to Increase its effective height.
• A rhombic antenna is a Non-resonant antenna.
• The carrier of a 100% modulated AM wave is suppressed, the % power saving is 66.66%.

Communication Systems

• Companding is the process in which the signal is first compressed before modulation and expanded after demodulation.
• Frequency shift keying is used mostly in Telegraphy.
• The carrier of a 100% modulated AM wave is suppressed, the % power saving is 66.66%.

Control Systems

• The knowledge of transfer function of a system is necessary for the calculation of Output for a given input, Steady state gain, Order of the system, Time constant, and All of the above.
• The most commonly used transistor arrangement is Common emitter.
• The SCR is a Uni-directional device.

Electrical Machines

• The shunt derived series fed feedback in an amplifier is used in Buchholz's relay.
• Buchholz's relay is used on transformers.

Measurement and Instrumentation

• The instrument used for DC measurement alone is the Permanent magnet type.
• The moving iron ammeter coil has few turns of thick wire in order to have Low resistance.
• The accuracy of an instrument is defined as the measure of instrument by which it Is error free.

Digital Electronics

• A digital signal is Discrete in both amplitude and time.
• A diode that has a negative resistance characteristic is the Tunnel diode.
• The duration of pulse response is finite for FIR filters.

Microcontrollers

• The flag register in 8051 microcontroller is the Program status word.

Miscellaneous

• Quality factor (Q-factor) of tuned circuit is referred to as the Selectivity property.
• Consistency of an instrument is related with Reliability.
• An oscillator converts DC power input to AC waveform signal.