First Year (FE)
- How is the calorific value of a solid fuel determined using a bomb calorimeter? In one line A known mass of fuel is burnt in excess oxygen inside a sealed steel "bomb" placed in a known mass of water, and the rise in wat... 1
- How does Boys' gas calorimeter measure the calorific value of a gaseous fuel? In one line A known volume of gas is burnt at a steady rate, and its heat is absorbed by water flowing through cooling tubes; from the water... 1
- How do you calculate the calorific value of coal using Dulong's formula? In one line Dulong's formula estimates the higher calorific value of a fuel from its percentages of carbon, hydrogen, oxygen and sulphur (fr... 1
- How do you calculate the minimum weight of oxygen and air needed to burn 1 kg of coal? In one line Using balanced combustion equations, find the oxygen needed by C, H and S, subtract the oxygen already present in the fuel, and... 1
- What is proximate analysis of coal and why do moisture, volatile matter, ash and fixed carbon matter? In one line Proximate analysis finds the percentages of moisture, volatile matter, ash and fixed carbon in coal by simple weighing and heati... 1
- How do you find the volume of air at STP needed to burn coal, including excess air? In one line Convert the minimum mass of oxygen into moles, multiply by 22.4 to get its volume at STP, then divide by 0.21 because air contai... 1
- What is ultimate analysis of coal and how are carbon, hydrogen, nitrogen, sulphur and oxygen found? In one line Ultimate analysis determines the elemental composition of coal (C, H, N, S, ash and O by difference) and is used for calorific v... 1
- What are polymers and macromolecules, and what do monomer and degree of polymerisation mean? In one line A polymer is a macromolecule (very large molecule, molecular weight typically 10³ to 10⁷) built by joining many small repeating... 1
- What chemical bonds and intermolecular forces hold polymer chains together? In one line Atoms within a polymer chain are joined by strong primary covalent bonds, while separate chains are held together by weaker seco... 1
- What is the difference between direct band gap and indirect band gap semiconductors? In one line In a direct band gap semiconductor the conduction band minimum and valence band maximum occur at the same crystal momentum k , s... 1
- How is the electrical conductivity of an intrinsic and extrinsic semiconductor expressed? In one line The conductivity of a semiconductor is σ = e(nμ_e + pμ_h) , the sum of contributions from electrons and holes; for intrinsic mat... 1
- What is drift velocity of charge carriers and how is it related to current? In one line Drift velocity is the small average velocity that free electrons (or holes) acquire in the direction set by an applied electric... 1
- What is mobility of charge carriers and what factors affect it? In one line Mobility is the drift velocity acquired by a charge carrier per unit electric field, μ = v_d/E , and it measures how easily carr... 1
- How is the electrical conductivity of a metallic conductor derived in terms of drift velocity and mobility? In one line In a metal the current density is J = nev_d = neμ E , so conductivity is σ = neμ = ne²τ/m , set by the free-electron density and... 1
- What is the Fermi-Dirac distribution function and how does it behave at different temperatures? In one line The Fermi-Dirac distribution function f(E) = 1/(1 + e^((E - E_F)/kT)) gives the probability that an electron energy state E is o... 1
- Why does the Fermi level lie at the middle of the band gap in an intrinsic semiconductor? In one line In an intrinsic semiconductor the number of electrons in the conduction band equals the number of holes in the valence band, and... 1
- Where does the Fermi level lie in n-type and p-type extrinsic semiconductors, and why? In one line In an n-type semiconductor the Fermi level lies close to the conduction band (between the donor level and E_c at 0 K), and in a... 1
- How does the Fermi level in extrinsic semiconductors shift with temperature and doping concentration? In one line As temperature rises, the Fermi level of both n-type and p-type semiconductors moves towards the middle of the gap (the material... 1
- What does the Gauss divergence theorem state and how is it used in electrodynamics? In one line The divergence theorem states that the total outward flux of a vector field through a closed surface equals the volume integral... 1
- What does Stokes' theorem state and how is it used to derive Maxwell's curl equations? In one line Stokes' theorem states that the line integral of a vector field around a closed loop equals the surface integral of its curl ove... 1
- What are Maxwell's equations in point (differential) form and how are they derived? In one line Maxwell's four equations in point form are nabla·D = ρ , nabla·B = 0 , nabla×E = -∂B/∂ t and nabla×H = J + ∂D/∂ t , describing e... 1
- What are Maxwell's equations in integral form and what does each one mean physically? In one line In integral form, Maxwell's equations relate the flux of D and B through closed surfaces, and the circulation of E and H around... 1
- Why are Maxwell's equations significant and what is the role of displacement current? In one line Maxwell's equations unify electricity, magnetism and light into one theory, and Maxwell's displacement current term made them co... 1
- What is de Broglie's hypothesis of matter waves and why was it proposed? In one line De Broglie proposed that every moving particle has a wave associated with it, with wavelength λ = h/p , just as light waves show... 1