AIIMS Nursing (BSc) Entrance 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. In SHM, where are velocity and acceleration maximum and minimum?

   Velocity is maximum at the mean position and zero at the extremes; acceleration is zero at the mean position and maximum at the extremes.

2. Differentiate between transverse and longitudinal waves with examples.

   Transverse: particles vibrate perpendicular to wave direction (e.g., light, waves on a string). Longitudinal: particles vibrate parallel to wave direction, forming compressions and rarefactions (e.g., sound in air).

3. Write the wave relation connecting speed, frequency, and wavelength.

   v = f λ, where v is wave speed, f is frequency, and λ is wavelength.

4. What are beats and the formula for beat frequency?

   Beats are periodic variations in sound intensity due to superposition of two waves of slightly different frequencies; beat frequency = |f1 - f2|.

5. State the Doppler effect for sound.

   The apparent change in frequency of sound due to relative motion between source and observer; apparent frequency f' = f (v ± v_o)/(v ∓ v_s), where v is sound speed, v_o observer speed, v_s source speed.

6. State Coulomb's law of electrostatics.

   The force between two point charges is F = k q1 q2 / r^2 (k = 1/4πε₀ = 9 x 10^9 N m^2 C^-2 in vacuum), directed along the line joining the charges.

7. Define electric field intensity and electric potential.

   Electric field E = force per unit positive charge = F/q (N/C or V/m, a vector). Electric potential V = work done per unit charge to bring it from infinity to a point (volt, a scalar).

8. Give the formula for the capacitance of a parallel-plate capacitor and energy stored.

   C = ε₀A/d (with a dielectric, multiply by k). Energy stored U = (1/2)CV^2 = (1/2)QV = Q^2/(2C).

9. State Ohm's law and define resistance and resistivity.

   Ohm's law: V = IR at constant temperature. Resistance R = V/I (ohm). Resistivity ρ relates by R = ρL/A; it is a material property independent of dimensions.

10. Write the formulae for resistors in series and in parallel.

    Series: R = R1 + R2 + R3 + ... Parallel: 1/R = 1/R1 + 1/R2 + 1/R3 + ...

11. State Kirchhoff's two laws for electric circuits.

    Junction (current) law: the sum of currents entering a junction equals the sum leaving (charge conservation). Loop (voltage) law: the algebraic sum of EMFs and potential drops around any closed loop is zero (energy conservation).

12. State the right-hand rule and the formula for force on a current-carrying conductor in a magnetic field.

    Force F = BIL sinθ, where B is magnetic field, I current, L length, θ angle between I and B. The right-hand rule gives the force direction perpendicular to both I and B.

13. State Faraday's laws of electromagnetic induction and Lenz's law.

    Faraday: an induced EMF is produced when magnetic flux through a circuit changes, with magnitude EMF = -dΦ/dt. Lenz's law: the induced current opposes the change in flux causing it (gives the minus sign, conserving energy).

14. For a transformer, write the turns ratio relation and state which type steps voltage up.

    Vs/Vp = Ns/Np = Ip/Is (for an ideal transformer). A step-up transformer has more turns in the secondary (Ns > Np), increasing voltage.

15. State the laws of reflection and the mirror formula.

    Laws of reflection: angle of incidence = angle of reflection, and incident ray, reflected ray, and normal lie in one plane. Mirror formula: 1/f = 1/v + 1/u.

16. State Snell's law and the lens maker's/thin-lens formula.

    Snell's law: n1 sin i = n2 sin r (refractive index n = sin i/sin r). Thin-lens formula: 1/f = 1/v - 1/u; power P = 1/f (in dioptres).

17. What is total internal reflection and the condition for it?

    When light travels from a denser to a rarer medium and the angle of incidence exceeds the critical angle, it is fully reflected back into the denser medium. Condition: i > critical angle C, where sin C = 1/n.

18. State Young's double-slit fringe width formula and the condition for interference.

    Fringe width β = λD/d, where D is slit-to-screen distance and d slit separation. Sustained interference requires two coherent sources (constant phase difference, same frequency).

19. State the photoelectric equation and define work function.

    Einstein's photoelectric equation: hf = φ + (1/2)mv²max, where hf is photon energy, φ the work function (minimum energy to eject an electron), and the rest is the electron's max KE.

20. State de Broglie's hypothesis and the wavelength formula.

    Moving particles have an associated wave; de Broglie wavelength λ = h/p = h/mv, where h is Planck's constant and p the momentum.

21. State Bohr's postulates for the hydrogen atom and the energy of the nth level.

    Electrons revolve in stationary orbits where angular momentum mvr = nh/2π, radiating energy only when jumping between orbits (E = hf). Energy of nth level: En = -13.6/n² eV.

22. Differentiate between nuclear fission and nuclear fusion.

    Fission: a heavy nucleus splits into lighter nuclei releasing energy (e.g., uranium in reactors). Fusion: light nuclei combine to form a heavier nucleus releasing energy (e.g., in the Sun). Both release energy due to mass defect (E = mc²).

23. Distinguish between intrinsic and extrinsic semiconductors, and between p-type and n-type.

    Intrinsic: pure semiconductor (Si, Ge). Extrinsic: doped semiconductor. n-type: doped with pentavalent impurity, electrons are majority carriers; p-type: doped with trivalent impurity, holes are majority carriers.

24. What is a p-n junction diode and what is meant by forward and reverse bias?

    A p-n junction diode allows current mainly in one direction. Forward bias (p to +, n to -) lowers the barrier and conducts; reverse bias raises the barrier and blocks current. Its main use is rectification (AC to DC).

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