Mixed Deck — All BEE Topics Flashcards

What does the term 'infinite bus' represent in power system analysis?

Answer: A bus with constant voltage and frequency regardless of load

An infinite bus is an idealized source with constant voltage magnitude and frequency, used as a reference in stability studies.

The built-in potential (contact potential) of a p-n junction at thermal equilibrium is caused by:

Answer: Diffusion of majority carriers and resulting charge separation

Diffusion of holes into the n-side and electrons into the p-side creates charge separation, establishing the built-in potential.

What is the output of a D flip-flop on the rising clock edge when D=0 and the current state Q=1?

Answer: Q becomes 0

A D flip-flop samples D on the active clock edge and transfers it directly to Q, so Q becomes 0 regardless of the previous state.

In a 4-bit binary ripple counter, what is the maximum count value before it resets to zero?

Answer: 15

A 4-bit counter counts from 0 to 2^4 − 1 = 15 before rolling over to zero.

In a series RLC circuit at resonance, which statement is correct?

Answer: Impedance equals R only

At resonance, XL = XC, so they cancel and total impedance equals R alone.

What is the function of a priority encoder with inputs I0–I3?

Answer: Outputs the binary code of the highest-priority active input

A priority encoder resolves simultaneous active inputs by outputting the binary code corresponding to the highest-priority (usually highest-numbered) active input.

What is the main advantage of HVDC transmission over HVAC for very long distance bulk power transfer?

Answer: Lower transmission losses due to absence of reactive power losses

HVDC eliminates reactive power losses and has lower resistive losses per unit length, making it more efficient for long-distance transmission.

What is the reactive power in a circuit where V = 100 V, I = 5 A, and the power factor angle θ = 30°?

Answer: 250 VAR

Q = V·I·sin θ = 100 × 5 × sin 30° = 500 × 0.5 = 250 VAR.

Which number system uses base 16 and includes digits 0-9 and letters A-F?

Answer: Hexadecimal

Hexadecimal (base-16) uses digits 0–9 and letters A–F to represent values 0–15 in a single digit, commonly used in digital systems.

What is the primary architectural difference that distinguishes a Von Neumann architecture from a Harvard architecture in microprocessors?

Answer: The organization of memory and buses for instructions and data.

The key difference lies in the memory structure. A Von Neumann architecture uses a single, shared memory and a common bus for both program instructions and data. In contrast, a Harvard architecture uses physically separate memories and separate buses for instructions and data, which allows the CPU to fetch an instruction and access data simultaneously, potentially overcoming the 'Von Neumann bottleneck'.

If the clock is low and D = 0, what will the output of a D flip-flop be?

Answer: No change

A D flip-flop is a synchronous device, meaning its output (Q) can only change state on the active edge of the clock signal (either positive or negative edge, depending on its design). If the clock is low, the flip-flop is in a 'hold' state, and its output will retain its previous value, regardless of the current state of the D input. Thus, there will be no change in the output.

What is the skin effect in transmission line conductors?

Answer: Increase in conductor resistance at high frequencies due to current crowding near the surface

At higher frequencies, eddy currents push current toward the conductor surface, effectively reducing the cross-sectional area and increasing resistance.

What may be measured using Maxwell's Inductance Capacitance Bridge?

Answer: Inductance

Maxwell's Inductance Capacitance Bridge is a specific type of AC bridge circuit primarily used for the precise measurement of unknown inductance. It operates by comparing the unknown inductance with a known standard capacitance. This bridge is particularly well-suited for measuring inductors with a medium Q-factor, providing accurate results by balancing the reactive components.

The directivity of an isotropic radiator is:

Answer: 1 (0 dBi)

An isotropic antenna radiates equally in all directions, so its directivity is defined as unity (0 dBi).

The sensitivity function S(s) = 1/[1 + G(s)H(s)] in a feedback control system quantifies:

Answer: How much the closed-loop transfer function changes relative to changes in the plant

The sensitivity function S(s) measures the relative change in closed-loop transfer function due to relative changes in the plant G(s), with small |S| indicating robustness.

What does the term 'fan-out' refer to in digital logic?

Answer: The maximum number of gate inputs that a gate output can reliably drive

Fan-out specifies how many standard gate inputs the output of a given gate can drive while maintaining valid logic levels.

What does a system's gain margin represent?

Answer: The factor by which gain can increase before the system becomes unstable

Gain margin is the reciprocal of the open-loop gain magnitude at the phase crossover frequency, indicating how much gain increase causes instability.

In a star (Y) connected three-phase system, the relationship between line voltage (V_L) and phase voltage (V_ph) is:

Answer: V_L = √3 × V_ph

In a balanced Y connection, the line voltage is √3 times the phase voltage.

In a common-emitter BJT amplifier, increasing the collector resistance RC while keeping other parameters fixed will:

Answer: Increase voltage gain

Voltage gain Av = -gm·RC, so increasing RC directly increases the magnitude of voltage gain.

Which boundary condition holds for the tangential component of the electric field at an interface between two perfect dielectrics?

Answer: E_t1 = E_t2

The tangential component of the electric field is continuous across a boundary between two dielectrics with no surface charge.