AMUEEE Physics Flashcards

24 sample cards from the Physics deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. State the condition for resonance in an LCR series circuit and the resonant frequency.

   Resonance occurs when X_L = X_C, giving minimum impedance Z = R and maximum current. Resonant frequency f₀ = 1/(2π√(LC)).

2. Relate rms and peak values of AC, and define the power factor.

   I_rms = I₀/√2, V_rms = V₀/√2. Average power P = V_rms I_rms cosφ; power factor = cosφ = R/Z.

3. What is the source of electromagnetic waves and their speed in vacuum?

   EM waves are produced by accelerating (oscillating) charges. They are transverse, with mutually perpendicular E and B fields, travelling at c = 1/√(μ₀ε₀) = 3 x 10^8 m/s in vacuum.

4. List the electromagnetic spectrum in order of increasing frequency.

   Radio waves < microwaves < infrared < visible light < ultraviolet < X-rays < gamma rays (frequency increases, wavelength decreases in this order).

5. State the laws of reflection and refraction (Snell's law).

   Reflection: angle of incidence = angle of reflection; incident ray, reflected ray, and normal are coplanar. Snell's law: n1 sinθ1 = n2 sinθ2 (refractive index x sine of angle is constant).

6. Give the mirror formula, lens formula, and definition of power of a lens.

   Mirror: 1/v + 1/u = 1/f. Lens: 1/v - 1/u = 1/f. Power P = 1/f (in metres), measured in dioptres (D).

7. State the condition for total internal reflection and the critical angle relation.

   TIR occurs when light travels from a denser to a rarer medium at an angle greater than the critical angle θ_c, where sinθ_c = 1/n (n = refractive index of denser medium relative to rarer).

8. Give the lensmaker's formula and the relation between focal length and refractive index.

   Lensmaker's formula: 1/f = (n - 1)(1/R1 - 1/R2), where n is the lens material's refractive index relative to the surrounding medium and R1, R2 are the radii of curvature.

9. State the condition for constructive and destructive interference in Young's double-slit experiment.

   Constructive (bright): path difference = nλ. Destructive (dark): path difference = (n + ½)λ. Fringe width β = λD/d (D = slit-to-screen distance, d = slit separation).

10. What is diffraction, and where does the first minimum occur in single-slit diffraction?

    Diffraction is the bending of waves around obstacles/edges and spreading after a slit. First minimum (single slit of width a): a sinθ = λ. Central maximum is the brightest and twice as wide.

11. State Huygens' principle and the result of polarisation (Malus's law).

    Huygens' principle: every point on a wavefront acts as a source of secondary wavelets; their envelope gives the new wavefront. Malus's law: I = I₀ cos^2θ (intensity through a polariser at angle θ to incident polarisation).

12. State the photoelectric effect equation and define work function and threshold frequency.

    Einstein's equation: hf = φ + KE_max, where φ = work function (minimum energy to eject an electron) = hf₀, and f₀ = threshold frequency below which no emission occurs.

13. Give the de Broglie wavelength of a particle.

    λ = h/p = h/(mv), where h = Planck's constant. For an electron accelerated through potential V: λ = 12.27/√V Å.

14. State the key observations of the photoelectric effect that classical physics could not explain.

    Emission is instantaneous; KE_max depends on frequency (not intensity); current depends on intensity; below threshold frequency no emission occurs regardless of intensity. These confirm the photon (quantum) nature of light.

15. State Bohr's postulates for the hydrogen atom.

    1) Electrons orbit in stationary states without radiating. 2) Angular momentum is quantised: L = nh/2π. 3) Radiation is emitted/absorbed when an electron jumps between orbits: hf = E2 - E1.

16. Give the energy of the nth level of hydrogen and the Rydberg formula for spectral lines.

    E_n = -13.6/n^2 eV. Rydberg formula: 1/λ = R(1/n1^2 - 1/n2^2), with R = 1.097 x 10^7 m^-1.

17. Define mass defect, binding energy, and the law of radioactive decay.

    Mass defect Δm = (mass of nucleons) - (mass of nucleus). Binding energy = Δm·c^2. Radioactive decay: N = N₀ e^(-λt), with half-life T½ = 0.693/λ.

18. Distinguish among alpha, beta, and gamma radiation.

    Alpha: helium nucleus (He-4), low penetration, high ionisation. Beta: electron/positron, moderate penetration. Gamma: high-energy EM photon, highest penetration, no charge or mass.

19. Distinguish nuclear fission from nuclear fusion.

    Fission: a heavy nucleus splits into lighter nuclei releasing energy (e.g. U-235). Fusion: light nuclei combine into a heavier nucleus releasing energy (e.g. in stars). Both release energy because products have higher binding energy per nucleon.

20. Distinguish among conductors, insulators, and semiconductors by energy band gap.

    Conductors: overlapping/no gap (E_g ≈ 0). Insulators: large gap (E_g > 3 eV). Semiconductors: small gap (E_g ≈ 1 eV), e.g. Si (1.1 eV), Ge (0.7 eV).

21. Distinguish n-type and p-type semiconductors.

    n-type: doped with pentavalent impurity (e.g. P, As), majority carriers are electrons. p-type: doped with trivalent impurity (e.g. B, Al), majority carriers are holes.

22. Describe the behaviour of a p-n junction diode under forward and reverse bias.

    Forward bias (p to +, n to -): depletion layer narrows, low resistance, current flows easily. Reverse bias: depletion layer widens, high resistance, only tiny leakage current flows (until breakdown).

23. Give the truth tables (outputs) of the basic logic gates AND, OR, and NOT.

    AND: output 1 only when both inputs are 1. OR: output 1 if any input is 1. NOT: output is the inverse of the input (1→0, 0→1).

24. What is a half-wave and a full-wave rectifier, and what is a Zener diode used for?

    Half-wave rectifier converts only one half of the AC cycle to DC; full-wave (bridge) rectifier uses both halves. A Zener diode operates in reverse breakdown at a constant voltage and is used as a voltage regulator.

What this deck covers

Physics flashcards FAQ