Physics Most Important Topics

<p>&nbsp;</p><h1 data-end="401" data-start="337">📘 NEB Class 12 Physics – Most Important Questions (2080/2081)</h1> <blockquote data-end="584" data-start="402"> <p data-end="584" data-start="404">Chapter-wise collection of crucial short and long answer questions for NEB Class 12 Physics based on the latest curriculum and exam trends. Ideal for revision and exam preparation.</p> </blockquote> <hr data-end="589" data-start="586" /> <h2 data-end="614" data-start="591">📗 Unit 1: Mechanics</h2> <h3 data-end="642" data-start="616">🔹 Rotational Dynamics</h3> <ul data-end="942" data-start="643"> <li data-end="705" data-start="643"> <p data-end="705" data-start="645">Derive the expression for kinetic energy of a rotating body.</p> </li> <li data-end="756" data-start="706"> <p data-end="756" data-start="708">Define moment of inertia and radius of gyration.</p> </li> <li data-end="801" data-start="757"> <p data-end="801" data-start="759">Prove: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>I</mi><mo>=</mo><mi>M</mi><msup><mi>R</mi><mn>2</mn></msup></mrow><annotation encoding="application/x-tex">I = MR^2</annotation></semantics></math></span><span aria-hidden="true" class="katex-html"><span class="base"><span class="strut"></span><span class="mord mathnormal">I</span><span class="mspace"></span><span class="mrel">=</span><span class="mspace"></span></span><span class="base"><span class="strut"></span><span class="mord mathnormal">M</span><span class="mord"><span class="mord mathnormal">R</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist"><span class="pstrut"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span></span></span></span></span></span></span> for a circular ring.</p> </li> <li data-end="848" data-start="802"> <p data-end="848" data-start="804">Derive torque and angular momentum relation.</p> </li> <li data-end="906" data-start="849"> <p data-end="906" data-start="851">Conservation of angular momentum – statement and proof.</p> </li> <li data-end="942" data-start="907"> <p data-end="942" data-start="909">Explain rolling without slipping.</p> </li> </ul> <h3 data-end="979" data-start="944">🔹 Simple Harmonic Motion (SHM)</h3> <ul data-end="1176" data-start="980"> <li data-end="1036" data-start="980"> <p data-end="1036" data-start="982">What is SHM? Derive the equation <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>a</mi><mo>=</mo><mo>−</mo><msup><mi>ω</mi><mn>2</mn></msup><mi>x</mi></mrow><annotation encoding="application/x-tex">a = -\omega^2x</annotation></semantics></math></span><span aria-hidden="true" class="katex-html"><span class="base"><span class="strut"></span><span class="mord mathnormal">a</span><span class="mspace"></span><span class="mrel">=</span><span class="mspace"></span></span><span class="base"><span class="strut"></span><span class="mord">−</span><span class="mord"><span class="mord mathnormal">ω</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist"><span class="pstrut"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span></span></span></span><span class="mord mathnormal">x</span></span></span></span>.</p> </li> <li data-end="1067" data-start="1037"> <p data-end="1067" data-start="1039">Energy of a particle in SHM.</p> </li> <li data-end="1108" data-start="1068"> <p data-end="1108" data-start="1070">Period of vertical spring-mass system.</p> </li> <li data-end="1142" data-start="1109"> <p data-end="1142" data-start="1111">Damped and forced oscillations.</p> </li> <li data-end="1176" data-start="1143"> <p data-end="1176" data-start="1145">Define resonance with examples.</p> </li> </ul> <h3 data-end="1200" data-start="1178">🔹 Fluid Mechanics</h3> <ul data-end="1413" data-start="1201"> <li data-end="1243" data-start="1201"> <p data-end="1243" data-start="1203">State and explain Archimedes’ principle.</p> </li> <li data-end="1290" data-start="1244"> <p data-end="1290" data-start="1246">Derive Bernoulli’s theorem with application.</p> </li> <li data-end="1330" data-start="1291"> <p data-end="1330" data-start="1293">Define viscosity. Derive Stoke’s law.</p> </li> <li data-end="1373" data-start="1331"> <p data-end="1373" data-start="1333">Continuity equation and its application.</p> </li> <li data-end="1413" data-start="1374"> <p data-end="1413" data-start="1376">Surface tension and angle of contact.</p> </li> </ul> <hr data-end="1418" data-start="1415" /> <h2 data-end="1456" data-start="1420">🌡️ Unit 2: Heat &amp; Thermodynamics</h2> <h3 data-end="1492" data-start="1458">🔹 First Law of Thermodynamics</h3> <ul data-end="1659" data-start="1493"> <li data-end="1539" data-start="1493"> <p data-end="1539" data-start="1495">Derive: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi mathvariant="normal">Δ</mi><mi>Q</mi><mo>=</mo><mi mathvariant="normal">Δ</mi><mi>U</mi><mo>+</mo><mi mathvariant="normal">Δ</mi><mi>W</mi></mrow><annotation encoding="application/x-tex">\Delta Q = \Delta U + \Delta W</annotation></semantics></math></span><span aria-hidden="true" class="katex-html"><span class="base"><span class="strut"></span><span class="mord">Δ</span><span class="mord mathnormal">Q</span><span class="mspace"></span><span class="mrel">=</span><span class="mspace"></span></span><span class="base"><span class="strut"></span><span class="mord">Δ</span><span class="mord mathnormal">U</span><span class="mspace"></span><span class="mbin">+</span><span class="mspace"></span></span><span class="base"><span class="strut"></span><span class="mord">Δ</span><span class="mord mathnormal">W</span></span></span></span></p> </li> <li data-end="1575" data-start="1540"> <p data-end="1575" data-start="1542">Cp and Cv relation for ideal gas.</p> </li> <li data-end="1626" data-start="1576"> <p data-end="1626" data-start="1578">Work done in isothermal and adiabatic processes.</p> </li> <li data-end="1659" data-start="1627"> <p data-end="1659" data-start="1629">Adiabatic equation derivation.</p> </li> </ul> <h3 data-end="1688" data-start="1661">🔹 Second Law &amp; Engines</h3> <ul data-end="1819" data-start="1689"> <li data-end="1714" data-start="1689"> <p data-end="1714" data-start="1691">State Carnot’s theorem.</p> </li> <li data-end="1752" data-start="1715"> <p data-end="1752" data-start="1717">Derive efficiency of Carnot engine.</p> </li> <li data-end="1787" data-start="1753"> <p data-end="1787" data-start="1755">Compare Otto and Diesel engines.</p> </li> <li data-end="1819" data-start="1788"> <p data-end="1819" data-start="1790">Entropy: concept and formula.</p> </li> </ul> <hr data-end="1824" data-start="1821" /> <h2 data-end="1854" data-start="1826">🌊 Unit 3: Waves &amp; Optics</h2> <h3 data-end="1874" data-start="1856">🔹 Wave Motion</h3> <ul data-end="1972" data-start="1875"> <li data-end="1911" data-start="1875"> <p data-end="1911" data-start="1877">Transverse and longitudinal waves.</p> </li> <li data-end="1945" data-start="1912"> <p data-end="1945" data-start="1914">Equation of a progressive wave.</p> </li> <li data-end="1972" data-start="1946"> <p data-end="1972" data-start="1948">Superposition principle.</p> </li> </ul> <h3 data-end="2005" data-start="1974">🔹 Stationary Waves &amp; Sound</h3> <ul data-end="2114" data-start="2006"> <li data-end="2043" data-start="2006"> <p data-end="2043" data-start="2008">Harmonics in open and closed pipes.</p> </li> <li data-end="2067" data-start="2044"> <p data-end="2067" data-start="2046">Laplace’s correction.</p> </li> <li data-end="2114" data-start="2068"> <p data-end="2114" data-start="2070">Doppler effect (source and observer motion).</p> </li> </ul> <h3 data-end="2149" data-start="2116">🔹 Interference &amp; Diffraction</h3> <ul data-end="2333" data-start="2150"> <li data-end="2195" data-start="2150"> <p data-end="2195" data-start="2152">Young’s double-slit experiment: Derivation.</p> </li> <li data-end="2255" data-start="2196"> <p data-end="2255" data-start="2198">Conditions for constructive and destructive interference.</p> </li> <li data-end="2290" data-start="2256"> <p data-end="2290" data-start="2258">Single-slit diffraction pattern.</p> </li> <li data-end="2333" data-start="2291"> <p data-end="2333" data-start="2293">Diffraction grating and resolving power.</p> </li> </ul> <h3 data-end="2354" data-start="2335">🔹 Polarization</h3> <ul data-end="2420" data-start="2355"> <li data-end="2387" data-start="2355"> <p data-end="2387" data-start="2357">Explain plane polarized light.</p> </li> <li data-end="2420" data-start="2388"> <p data-end="2420" data-start="2390">Brewster’s law and Malus’ law.</p> </li> </ul> <hr data-end="2425" data-start="2422" /> <h2 data-end="2463" data-start="2427">⚡ Unit 4: Electricity &amp; Magnetism</h2> <h3 data-end="2491" data-start="2465">🔹 Electrical Circuits</h3> <ul data-end="2664" data-start="2492"> <li data-end="2526" data-start="2492"> <p data-end="2526" data-start="2494">Kirchhoff’s laws with numerical.</p> </li> <li data-end="2572" data-start="2527"> <p data-end="2572" data-start="2529">Wheatstone bridge &amp; meter bridge principle.</p> </li> <li data-end="2609" data-start="2573"> <p data-end="2609" data-start="2575">Potentiometer: principle and uses.</p> </li> <li data-end="2664" data-start="2610"> <p data-end="2664" data-start="2612">Conversion of galvanometer to ammeter and voltmeter.</p> </li> </ul> <h3 data-end="2682" data-start="2666">🔹 Magnetism</h3> <ul data-end="2827" data-start="2683"> <li data-end="2721" data-start="2683"> <p data-end="2721" data-start="2685">Biot-Savart law and its application.</p> </li> <li data-end="2747" data-start="2722"> <p data-end="2747" data-start="2724">Ampere’s circuital law.</p> </li> <li data-end="2782" data-start="2748"> <p data-end="2782" data-start="2750">Force between parallel currents.</p> </li> <li data-end="2827" data-start="2783"> <p data-end="2827" data-start="2785">Magnetic field due to solenoid and toroid.</p> </li> </ul> <h3 data-end="2861" data-start="2829">🔹 Electromagnetic Induction</h3> <ul data-end="2990" data-start="2862"> <li data-end="2894" data-start="2862"> <p data-end="2894" data-start="2864">Faraday’s laws and Lenz’s law.</p> </li> <li data-end="2934" data-start="2895"> <p data-end="2934" data-start="2897">Eddy currents and their applications.</p> </li> <li data-end="2964" data-start="2935"> <p data-end="2964" data-start="2937">Mutual and self-inductance.</p> </li> <li data-end="2990" data-start="2965"> <p data-end="2990" data-start="2967">Working of transformer.</p> </li> </ul> <h3 data-end="3023" data-start="2992">🔹 Alternating Current (AC)</h3> <ul data-end="3167" data-start="3024"> <li data-end="3068" data-start="3024"> <p data-end="3068" data-start="3026">Define peak, rms, and average value of AC.</p> </li> <li data-end="3110" data-start="3069"> <p data-end="3110" data-start="3071">Derive current in R, L, and C circuits.</p> </li> <li data-end="3139" data-start="3111"> <p data-end="3139" data-start="3113">AC power and power factor.</p> </li> <li data-end="3167" data-start="3140"> <p data-end="3167" data-start="3142">Resonance in LCR circuit.</p> </li> </ul> <hr data-end="3172" data-start="3169" /> <h2 data-end="3202" data-start="3174">🔬 Unit 5: Modern Physics</h2> <h3 data-end="3231" data-start="3204">🔹 Photoelectric Effect</h3> <ul data-end="3345" data-start="3232"> <li data-end="3268" data-start="3232"> <p data-end="3268" data-start="3234">Einstein’s photoelectric equation.</p> </li> <li data-end="3311" data-start="3269"> <p data-end="3311" data-start="3271">Characteristics of photoelectric effect.</p> </li> <li data-end="3345" data-start="3312"> <p data-end="3345" data-start="3314">Millikan’s oil drop experiment.</p> </li> </ul> <h3 data-end="3368" data-start="3347">🔹 Semiconductors</h3> <ul data-end="3527" data-start="3369"> <li data-end="3415" data-start="3369"> <p data-end="3415" data-start="3371">PN junction diode: forward and reverse bias.</p> </li> <li data-end="3472" data-start="3416"> <p data-end="3472" data-start="3418">Zener diode and its application in voltage regulation.</p> </li> <li data-end="3527" data-start="3473"> <p data-end="3527" data-start="3475">Logic gates: AND, OR, NOT, NAND, NOR – truth tables.</p> </li> </ul> <h3 data-end="3550" data-start="3529">🔹 Atomic Physics</h3> <ul data-end="3674" data-start="3551"> <li data-end="3607" data-start="3551"> <p data-end="3607" data-start="3553">Bohr’s postulates and derivation of radius and energy.</p> </li> <li data-end="3645" data-start="3608"> <p data-end="3645" data-start="3610">de Broglie hypothesis and equation.</p> </li> <li data-end="3674" data-start="3646"> <p data-end="3674" data-start="3648">X-ray properties and uses.</p> </li> </ul> <h3 data-end="3698" data-start="3676">🔹 Nuclear Physics</h3> <ul data-end="3850" data-start="3699"> <li data-end="3732" data-start="3699"> <p data-end="3732" data-start="3701">Define half-life and mean life.</p> </li> <li data-end="3768" data-start="3733"> <p data-end="3768" data-start="3735">Derive the radioactive decay law.</p> </li> <li data-end="3798" data-start="3769"> <p data-end="3798" data-start="3771">Nuclear fission and fusion.</p> </li> <li data-end="3850" data-start="3799"> <p data-end="3850" data-start="3801">Use of radioisotopes in medicine and agriculture.</p> </li> </ul> <h3 data-end="3872" data-start="3852">🔹 Recent Trends</h3> <ul data-end="4024" data-start="3873"> <li data-end="3920" data-start="3873"> <p data-end="3920" data-start="3875">Earthquake waves: P, S, Love, Rayleigh waves.</p> </li> <li data-end="3969" data-start="3921"> <p data-end="3969" data-start="3923">Basics of nanotechnology and its applications.</p> </li> <li data-end="4024" data-start="3970"> <p data-end="4024" data-start="3972">Introduction to gravitational waves and Higgs boson.</p></li></ul>