Engineering Physics-II Quiz

What is the main factor that determines the conductivity of a material?

• Presence of free protons

• Presence of free neutrons

• Presence of free electrons

• Presence of free positrons

Which of the following materials are examples of conducting materials?

• Aluminum, Titanium, Lead

• Plastic, Wood, Glass

• Iron, Zinc, Nickel

• Gold, Silver, Copper

What is the average velocity of free electrons with which they move towards the positive terminal under the influence of an electrical field?

• Drift velocity

• Collision time

• Mean free path

• Relaxation time

What is the definition of mobility in the context of conducting materials?

• Average distance traveled by a free electron between two successive collisions

• Rate of charge flow across unit area

• Drift velocity of the charge carrier per unit applied electric field

• Average time taken by a free electron between two successive collisions

What is the expression for electrical conductivity in a conductor?

• σ = m / e

• σ = 2mneτ

• σ = E / J

• σ = nev_d

What is the definition of thermal conductivity in a material?

• Amount of heat flowing per unit time through the material per unit temperature gradient

• Rate of charge flow across unit area

• Average time taken by a free electron between two successive collisions

• Average distance traveled by a free electron between two successive collisions

According to the Wiedemann – Franz law, what is the relationship between thermal conductivity and electrical conductivity of a metal?

• They are inversely proportional

• They are inversely proportional to the square of the absolute temperature

• They are directly proportional

• They are not related

What does the Fermi-Dirac distribution function represent?

• Probability of an electron occupying a given energy level at absolute temperature

• Average time taken by a free electron between two successive collisions

• Rate of charge flow across unit area

• Average distance traveled by a free electron between two successive collisions

At what temperature does the Fermi function vary as a step function for different energy values?

• 0K

• 100K

• 500K

• 1000K

What does the density of energy states represent?

• Number of available electron states per unit volume in an Energy interval

• Average distance traveled by a free electron between two successive collisions

• Rate of charge flow across unit area

• Average time taken by a free electron between two successive collisions