Electrical, Thermodynamics & Fluid Systems Flashcards

In an op-amp inverting amplifier with R_f = 100 kΩ and R_in = 10 kΩ, the voltage gain is:

Answer: −10

Inverting amplifier gain A_v = −R_f / R_in = −100/10 = −10.

The major head loss in a pipe system is primarily due to:

Answer: Pipe wall friction over the pipe length

Major (Darcy-Weisbach) losses arise from friction along the straight length of the pipe; minor losses come from fittings.

An isentropic process is one that is both:

Answer: Reversible and adiabatic

An isentropic (constant entropy) process requires both adiabatic (no heat transfer) and reversible conditions.

A magnetic flux of 0.5 Wb through a 200-turn coil changes to zero in 0.1 s. The average induced EMF is:

Answer: 1000 V

EMF = −N ΔΦ/Δt = −200 × (0 − 0.5)/0.1 = 1000 V (magnitude).

The specific speed of a pump is used to:

Answer: Classify pump type and predict performance at varying scales

Specific speed N_s = N√Q / H^(3/4) classifies pumps (centrifugal, mixed, axial) and guides selection and scaling.

The thermal efficiency of an ideal Otto cycle with a compression ratio r = 8 (γ = 1.4) is approximately:

Answer: 56.5%

η_Otto = 1 − 1/r^(γ−1) = 1 − 1/8^0.4 ≈ 1 − 0.435 = 0.565 or 56.5%.

For a Newtonian fluid, shear stress τ is related to the velocity gradient du/dy by:

Answer: τ = μ (du/dy)

Newton's law of viscosity defines a Newtonian fluid: τ = μ du/dy, where μ is dynamic viscosity.