Technical Textiles MCQs (Set-4)

Permittivity is 0.8 s⁻¹, head difference is 0.05 m and test area is 0.20 m². For a normal-flow test using Q = ψΔhA, what flow results?

Media efficiency is 99% for particles traversing it, but 4% of equal-concentration inlet flow bypasses the filter. What is system efficiency?

A unidirectional composite is loaded parallel to fibres. Let both phases have equal strain. Fibres are 50% by volume and have modulus 150 GPa, while matrix modulus is 3 GPa. Approximately what share of axial force is carried by fibres?

Across an assembly with area-specific thermal resistance 0.25 m²·K/W, temperature drops by 15 K. What steady heat flux does the simple model predict?

Using Q = θiw, find in-plane flow through a 4 m wide sheet with transmissivity 0.003 m²/s and gradient 0.5.

In a hygiene test, 30 g of dry core retains 210 g of liquid. How much liquid is retained per gram of dry core?

Fibre mass is 180 g at density 1.8 g/cm³ and resin mass is 120 g at density 1.2 g/cm³. With no voids, what is fibre volume fraction?

Two identical filter panels operate in parallel. At the same combined airflow as one panel, each panel carries half the flow. If pressure drop is linear in flow, how does overall pressure drop compare with one panel?

Radiation transmission through two layers is 20% and 10% of what reaches each one, with no interaction in a simple independent model. What overall fraction is transmitted?

A protective laminate passes a flat sample test but leaks after flexing along a seam. Which experimental comparison most directly checks the proposed failure location?

Mass gain of a moisture barrier sample is 18 g in 3 h through 0.03 m². Assuming constant rate, how much mass transfers per square metre per hour?

Under higher confinement, in-plane flow drops from 1.2 to 0.75 L/s at the same gradient. What percentage of original flow remains?

Assume ideal continuous aligned fibres at 60% volume, fibre modulus 200 GPa and matrix modulus 4 GPa. By the longitudinal rule of mixtures, what modulus is predicted?

What power is dissipated in a constant 12 Ω textile heating track with 6 V across it?

Two textile sheets are stacked in a normal-flow test. Each sheet alone would have the same head loss at a given flow. If their head losses add and the total head stays fixed, how does the stack flow compare with one sheet in the linear model?

First filter stage removes 80% of incoming particles and the second removes 90% of particles reaching it. What overall efficiency results with no bypass?

Stretch increases film area by 25% and film volume is conserved. For a uniform layer, what is the new thickness relative to the old?

At 0.50 m³/s flow and 240 Pa pressure drop, what fluid power is needed to drive air through a filter, ignoring motor losses?

With 55% fibre by volume and no voids, what composite density follows from fibre and matrix densities of 1.8 and 1.2 g/cm³?

Two identical 12 Ω conductive textile paths connect the same two points in parallel. What equivalent resistance results?

Across a textile 4 mm thick, hydraulic conductivity is 0.002 m/s. Under ψ = k/t, what is permittivity?

One medium clogs sooner than another at matched airflow and dust loading, although initial particle collection is equal. Which performance curve distinguishes the media?

What thickness follows from a uniform panel’s areal mass of 1.2 kg/m² and bulk density of 1,500 kg/m³?

For a 6 mm insulator with conductivity 0.04 W/(m·K), calculate thermal resistance per unit area in the plane-layer model.

At constant volumetric flow, exposed filter area increases by 50%. What is the new face velocity as a fraction of the old?