Viva Questions PDF

Here are accurate and concise answers to all the previously mentioned questions: Electrostatics 1. What is Coulomb's law? Coulomb's law states that the electrostatic force between two point charges is directly proportional to the product of their charges and inversely proportional t...

Here are accurate and concise answers to all the previously mentioned questions: Electrostatics 1. What is Coulomb's law? Coulomb's law states that the electrostatic force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. Formula: F=k⋅q1⋅q2r2F = \frac{k \cdot q_1 \cdot q_2}{r^2}, where k=14πϵ0k = \frac{1}{4\pi \epsilon_0}. 2. Define electric field. The electric field at a point is the force experienced by a unit positive charge placed at that point. Formula: E=FqE = \frac{F}{q}. 3. Define electric potential. Electric potential at a point is the work done in bringing a unit positive charge from infinity to that point. Formula: V=WqV = \frac{W}{q}. Current Electricity 4. State Ohm's law. Ohm's law states that the current through a conductor is directly proportional to the potential difference across its ends, provided the temperature remains constant. Formula: V=IRV = IR. 5. What is the principle of a Wheatstone bridge? A Wheatstone bridge works on the principle of null deflection: the ratio of resistances in one arm equals the ratio in the other arm when no current flows through the galvanometer. Condition: R1R2=R3R4\frac{R_1}{R_2} = \frac{R_3}{R_4}. 6. How do resistances combine in series and parallel? In Series: Req=R1+R2+R3+…R_{\text{eq}} = R_1 + R_2 + R_3 + \dots In Parallel: 1Req=1R1+1R2+…\frac{1}{R_{\text{eq}}} = \frac{1}{R_1} + \frac{1}{R_2} + \dots Magnetic Effects of Current and Magnetism  7. What is Biot-Savart's law? Biot-Savart's law gives the magnetic field at a point due to a small current-carrying element. Formula: dB=μ04π⋅I dl sin⁡θr2dB = \frac{\mu_0}{4\pi} \cdot \frac{I \, dl \, \sin \theta}{r^2}. 8. Define Ampere's circuital law. The line integral of the magnetic field around a closed loop is equal to μ0\mu_0 times the total current enclosed by the loop. Formula: ∮B⃗⋅dl⃗=μ0Ienc\oint \vec{B} \cdot d\vec{l} = \mu_0 I_{\text{enc}}. 9. What is the difference between diamagnetic, paramagnetic, and ferromagnetic substances? o Diamagnetic: Weakly repelled by a magnetic field (e.g., bismuth, copper). o Paramagnetic: Weakly attracted to a magnetic field (e.g., aluminum, platinum). o Ferromagnetic: Strongly attracted to a magnetic field and retain magnetism (e.g., iron, nickel). Electromagnetic Induction and Alternating Currents 10. State Faraday's laws of electromagnetic induction. o First Law: A changing magnetic flux induces an EMF in a conductor. o Second Law: The induced EMF is directly proportional to the rate of change of magnetic flux. Formula: EMF=−dΦBdt\text{EMF} = -\frac{d\Phi_B}{dt}. 11. What is Lenz’s law? The direction of the induced current opposes the change in magnetic flux that produces it. Significance: It ensures the conservation of energy. 12. What is the principle of a transformer? A transformer works on the principle of electromagnetic induction: a varying current in the primary coil induces an EMF in the secondary coil. Formula: VsVp=NsNp\frac{V_s}{V_p} = \frac{N_s}{N_p}. Optics  13. What is Snell’s law? Snell’s law relates the angles of incidence (θ1\theta_1) and refraction (θ2\theta_2) to the refractive indices of two media. Formula: n1sin⁡θ1=n2sin⁡θ2n_1 \sin \theta_1 = n_2 \sin \theta_2. 14. What are the conditions for total internal reflection? o Light must travel from a denser to a rarer medium. o The angle of incidence must exceed the critical angle (θc\theta_c). Critical Angle Formula: sin⁡θc=n2n1\sin \theta_c = \frac{n_2}{n_1}. 15. Explain the working of a compound microscope. A compound microscope uses two lenses: the objective lens (produces a magnified real image) and the eyepiece (magnifies the real image further). Formula for Magnification: M=Mo⋅MeM = M_o \cdot M_e. Dual Nature of Matter and Radiation 16. What is the photoelectric effect? The photoelectric effect is the emission of electrons from a metal surface when light of sufficient frequency strikes it. Einstein’s Equation: hν=ϕ+12mv2h\nu = \phi + \frac{1}{2} mv^2. 17. Define de Broglie wavelength. A moving particle has a wavelength associated with it, called the de Broglie wavelength. Formula: λ=hmv\lambda = \frac{h}{mv}. Atoms and Nuclei 18. What is nuclear fission? Nuclear fission is the splitting of a heavy nucleus into two lighter nuclei with the release of energy. 19. What is nuclear fusion? Nuclear fusion is the combining of two light nuclei to form a heavier nucleus, releasing energy. 20. Define mass defect and binding energy. o Mass defect: The difference between the mass of a nucleus and the sum of the masses of its nucleons.  o Binding energy: The energy required to split a nucleus into its constituent nucleons. Formula: Eb=Δmc2E_b = \Delta m c^2. Semiconductor Electronics 21. What is a PN junction diode? A PN junction diode is a semiconductor device that allows current to flow in one direction (forward bias) and blocks it in the reverse direction (reverse bias). 22. What are logic gates? Logic gates are digital circuits that perform logical operations. o AND gate: Y=A⋅BY = A \cdot B. o OR gate: Y=A+BY = A + B. o NOT gate: Y=A‾Y = \overline{A}. Let me know if you'd like further explanations or diagrams for any of these!