IIT JEE SET 7 WAVES & THERMODYNAMICS Physics Practice Paper Set 7 Waves · Sound · Thermodynamics · Kinetic Theory Questions: 30 Marks per correct: +4 Negative marking: None Max Score: 120 Suggested Time: 60 min 📋 Instructions Each question carries 4 marks. There is NO negative marking in this set. Select one option per question. Only your last selected option will be recorded. Click “Submit Paper” after attempting all questions. Unattempted questions will be counted as wrong (0 marks). Results with detailed explanations appear immediately after submission. Question 01 A string of length \(L\) is fixed at both ends and vibrates in its 3rd harmonic. The ratio of the wavelength of the standing wave to the length of the string is: A\( \dfrac{2}{3} \) B\( \dfrac{3}{2} \) C\( \dfrac{1}{3} \) D\( \dfrac{2}{1} \) Question 02 A train moving at 30 m/s emits a whistle of frequency 600 Hz. If the speed of sound is 330 m/s, the apparent frequency heard by a stationary observer standing behind the train is: A545.5 Hz B660 Hz C600 Hz D500 Hz Question 03 Two sound waves of frequencies 256 Hz and 260 Hz superpose. The number of beats heard per second is: A2 B4 C8 D516 Question 04 An open organ pipe of length 0.5 m resonates at its fundamental frequency. If speed of sound is 340 m/s, the fundamental frequency is: A170 Hz B340 Hz C680 Hz D85 Hz Question 05 The intensity of sound at a point is \(10^{-8}\) W/m². If the threshold intensity is \(10^{-12}\) W/m², the sound level in decibels is: A20 dB B40 dB C80 dB D60 dB Question 06 A closed organ pipe of length \(L\) produces its first overtone at the same frequency as the fundamental of an open pipe of length \(L’\). The ratio \(L : L’\) is: A1 : 2 B3 : 4 C2 : 3 D3 : 2 Question 07 A wave is represented by \(y = 5\sin(2\pi t – \frac{\pi x}{3})\) (SI units). The phase velocity of the wave is: A3 m/s B6 m/s C\(\dfrac{2}{3}\) m/s D\(2\pi\) m/s Question 08 In a stationary wave, the distance between two consecutive nodes is 0.3 m. The wavelength of the wave is: A0.15 m B0.3 m C0.6 m D1.2 m Question 09 The speed of sound in a gas at 27°C is \(v\). At what temperature (in °C) will the speed be \(2v\)? A54°C B108°C C927°C D1200°C Question 10 The tension in a string is quadrupled. The speed of the transverse wave in it will become: ADouble BHalf CFour times DSame Question 11 For an ideal gas undergoing an isothermal process, which of the following remains constant? APressure BVolume CInternal energy DEntropy Question 12 One mole of a monatomic ideal gas is taken through an adiabatic process. The ratio \(\gamma = C_p / C_v\) for a monatomic ideal gas is: A\(\dfrac{7}{5}\) B\(\dfrac{5}{3}\) C\(\dfrac{4}{3}\) D\(\dfrac{3}{2}\) Question 13 The work done by a gas in an isothermal expansion from volume \(V_1\) to \(V_2\) at temperature \(T\) is: A\(nRT \ln\!\left(\dfrac{V_2}{V_1}\right)\) B\(nRT(V_2 – V_1)\) C\(\dfrac{nR(T_2 – T_1)}{\gamma – 1}\) DZero Question 14 A Carnot engine operates between temperatures 500 K and 300 K. Its efficiency is: A40% B60% C30% D20% Question 15 According to the equipartition theorem, the internal energy of one mole of a diatomic gas (rigid) at temperature \(T\) is: A\(\dfrac{3}{2} RT\) B\(\dfrac{5}{2} RT\) C\(3 RT\) D\(2 RT\) Question 16 The rms speed of oxygen molecules at 27°C is approximately (M = 32 g/mol, R = 8.314 J/mol·K): A483 m/s B684 m/s C200 m/s D961 m/s Question 17 During an adiabatic process, the relation between pressure and volume is \(PV^\gamma = \text{const}\). For this process, the work done by the gas is: A\(\dfrac{P_1 V_1 – P_2 V_2}{\gamma – 1}\) B\(nRT\ln\!\left(\dfrac{V_2}{V_1}\right)\) C\(P(V_2 – V_1)\) DZero Question 18 A gas absorbs 600 J of heat and does 250 J of work. The change in internal energy of the gas is: A350 J B−350 J C850 J D600 J Question 19 The mean free path of a gas molecule is inversely proportional to: ATemperature BSquare of molecular diameter CNumber density \(\times\) diameter squared DPressure only Question 20 In a \(p\text{-}V\) diagram, an isochoric process is represented by: AA horizontal line BA curve \(pV = \text{const}\) CA vertical line DA curve \(pV^\gamma = \text{const}\) Question 21 Two waves \(y_1 = A\sin(\omega t)\) and \(y_2 = A\sin(\omega t + \phi)\) are superposed. For completely destructive interference, \(\phi\) must be: A\(0, 2\pi, 4\pi\ldots\) B\(\pi, 3\pi, 5\pi\ldots\) C\(\dfrac{\pi}{2}, \dfrac{3\pi}{2}\ldots\) DAny value of \(\phi\) Question 22 The velocity of sound in air at STP is about 332 m/s. At 100°C (373 K), the speed will be approximately: A366 m/s B332 m/s C432 m/s D664 m/s Question 23 Which of the following processes is represented by \(\Delta U = 0\)? AAdiabatic process BIsochoric process CIsothermal process (ideal gas) DIsobaric process Question 24 For a diatomic ideal gas, the ratio of the slope of the adiabatic curve to the slope of the isothermal curve (at the same point on the \(p\text{-}V\) diagram) is: A\(\dfrac{7}{5}\) B\(\dfrac{5}{3}\) C\(\dfrac{5}{7}\) D1 Question 25 The Doppler effect is NOT observed when: AThe source moves towards the observer BThe observer moves towards the source CBoth move perpendicular to the line joining them DThe medium moves between them Question 26 The number of degrees of freedom for a rigid diatomic molecule is: A3 B5 C6 D7 Question 27 A string vibrates in 4 loops when 36 g is suspended. To make it vibrate in 6 loops, the mass suspended should be: A16 g B24 g C64 g D9 g Question 28 For an ideal gas, at constant pressure, the graph of volume vs absolute temperature is: AA parabola BA straight line through the origin CA hyperbola DA horizontal line Question 29 If the pressure of a gas is doubled at constant volume, the rms speed of the gas molecules becomes: ASame B\(\sqrt{2}\) times CDouble D4 times Question 30 The second law of thermodynamics implies that: AEnergy is always conserved BHeat flows spontaneously from

IIT JEE Physics Practice Paper – Modern Physics (Set 6) Instructions Total Questions: 20 | Marks: 4 each | No Negative Marking Q1. Photoelectric effect proves: Particle nature of light Wave nature Both equally None Q2. Einstein photoelectric equation is: hν = φ + KE E = mc² V = IR None Q3. Threshold frequency depends on: Material Intensity Distance Time Q4. Work function is: Minimum energy to remove electron Maximum energy Kinetic energy None Q5. de Broglie wavelength is: h/p p/h hv None Q6. Planck constant unit is: J·s J W N Q7. Energy of photon is: hν mv² mc² None Q8. Compton effect proves: Particle nature Wave nature Both None Q9. Bohr model applies to: Hydrogen atom All atoms Molecules None Q10. Energy levels in atom are: Quantized Continuous Infinite None Q11. Radius of Bohr orbit proportional to: n² n 1/n None Q12. Nuclear force is: Short range Long range Infinite None Q13. Binding energy is: Energy to break nucleus Energy released Kinetic energy None Q14. Half-life depends on: Nature of substance Temperature Pressure Volume Q15. Radioactive decay is: Random Predictable Periodic None Q16. Mass-energy relation: E = mc² V = IR F = ma None Q17. Pair production requires: High energy photon Low energy photon Electron None Q18. Semiconductor conductivity increases with: Temperature Pressure Volume None Q19. Diode allows current in: One direction Both None Random Q20. Transistor is used for: Amplification Storage Reflection None Submit Modern Physics – IIT JEE Notes (Set 6) Photoelectric Effect Concept The photoelectric effect is the emission of electrons from a metal surface when light of sufficient frequency falls on it. It proves the particle nature of light. Einstein Equation hν = φ + KE(max) Where h is Planck’s constant, ν is frequency, φ is work function, and KE is kinetic energy of emitted electrons. Work Function and Threshold Frequency Work Function Minimum energy required to remove an electron from the surface of a metal. Threshold Frequency The minimum frequency required to initiate photoelectric emission. It depends only on the material. de Broglie Hypothesis Concept Every moving particle has wave nature associated with it. Formula λ = h/p Where λ is wavelength and p is momentum. Photon and Energy Quantization Photon Energy E = hν Key Insight Energy of light is quantized and comes in discrete packets called photons. Compton Effect Concept Scattering of X-rays by electrons leads to an increase in wavelength. Importance It confirms the particle nature of light and conservation of momentum. Bohr Model of Atom Postulates Electrons revolve in fixed orbits with quantized energy levels. Energy Levels E ∝ -1/n² Radius of Orbit r ∝ n² Atomic Spectra Concept When electrons transition between energy levels, they emit or absorb photons of specific wavelengths. Key Insight Each element has a unique spectral signature. Nuclear Physics Basics Nuclear Force Short-range force that holds protons and neutrons together inside nucleus. Binding Energy Energy required to separate a nucleus into individual nucleons. Radioactivity Decay Law N = N₀e^(-λt) Half-Life Time required for half of the radioactive substance to decay. It depends only on the nature of the nucleus. Key Insight Radioactive decay is random and unaffected by external conditions. Mass-Energy Equivalence Formula E = mc² Application Used to explain nuclear reactions like fission and fusion. Pair Production and Annihilation Pair Production A high-energy photon converts into an electron-positron pair in presence of a nucleus. Annihilation Electron and positron combine to produce energy in the form of photons. Semiconductors Types Intrinsic and Extrinsic (n-type and p-type). Key Insight Conductivity increases with temperature, unlike metals. Diodes and Transistors Diode Allows current to flow in one direction only. Transistor Used for amplification and switching in electronic circuits. Important Exam Concepts Conceptual Traps Intensity affects number of electrons emitted, not their energy. Frequency controls energy in photoelectric effect. JEE Strategy Focus on formulas, graphs, and conceptual clarity. Practice numerical problems on photoelectric effect and radioactive decay.

Go to Notes IIT JEE Practice Series Physics Practice PaperWaves & Oscillations 30 Concept-Based Questions | JEE Main & Advanced Level 📋 5 Parts ❓ 30 Questions ⏱ 60 Minutes 🏆 120 Marks ➕ +4 / No Negative 📌 Instructions Each question carries +4 marks for a correct answer. There is no negative marking. Select one option per question. Unattempted questions carry 0 marks. Click Submit Paper after attempting all questions to view your score and explanations. Topics: Simple Harmonic Motion, Wave Motion, Sound Waves, Doppler Effect, Superposition & Beats. Part I Simple Harmonic Motion — Fundamentals Q 01 A particle executes SHM with amplitude \(A\) and angular frequency \(\omega\). The ratio of maximum acceleration to maximum velocity is: A \(\dfrac{\omega}{A}\) B \(\omega A\) C \(\omega\) D \(\dfrac{A}{\omega}\) Q 02 In SHM, the total mechanical energy of a particle at displacement \(x\) from the mean position is: A \(\dfrac{1}{2}m\omega^2 x^2\) B \(\dfrac{1}{2}m\omega^2(A^2 – x^2)\) C \(\dfrac{1}{2}m\omega^2 A^2\) D \(m\omega^2 A^2\) Q 03 A particle in SHM has velocity \(v_1\) at displacement \(x_1\) and velocity \(v_2\) at displacement \(x_2\). The amplitude of oscillation is: A \(\sqrt{\dfrac{v_1^2 x_2^2 – v_2^2 x_1^2}{v_1^2 – v_2^2}}\) B \(\sqrt{\dfrac{v_1^2 x_1^2 – v_2^2 x_2^2}{v_2^2 – v_1^2}}\) C \(\sqrt{x_1^2 + x_2^2}\) D \(\sqrt{\dfrac{v_1^2 + v_2^2}{x_1^2 + x_2^2}}\) Q 04 The time period of a simple pendulum on the surface of a planet where gravitational acceleration is \(\dfrac{g}{4}\) compared to Earth is: A Same as on Earth B Half of Earth’s value C Double of Earth’s value D Four times Earth’s value Q 05 For a spring-mass system with spring constant \(k\) and mass \(m\), if the spring is cut into \(n\) equal parts and one part is used with the same mass, the new time period is: A \(T\sqrt{n}\) B \(\dfrac{T}{\sqrt{n}}\) C \(nT\) D \(\dfrac{T}{n}\) Q 06 The phase difference between displacement and velocity of a particle executing SHM is: A \(0\) B \(\pi\) C \(\dfrac{\pi}{2}\) D \(\dfrac{\pi}{4}\) Part II Simple Harmonic Motion — Advanced Q 07 Two particles perform SHM with the same amplitude and frequency but with a phase difference of \(\dfrac{\pi}{3}\). The maximum resultant displacement when they are superimposed is: A \(A\) B \(\sqrt{3}A\) C \(2A\) D \(\sqrt{2}A\) Q 08 A particle executes SHM: \(x = 5\sin\!\left(2\pi t + \dfrac{\pi}{4}\right)\) cm. The displacement at \(t = 0\) and the initial direction of motion are respectively: A \(5\sqrt{2}/2\) cm, towards positive \(x\) B \(5\) cm, towards positive \(x\) C \(5\sqrt{2}/2\) cm, towards negative \(x\) D \(0\) cm, towards positive \(x\) Q 09 A mass \(m\) is suspended from two springs of spring constants \(k_1\) and \(k_2\) connected in parallel. The angular frequency of oscillation is: A \(\sqrt{\dfrac{k_1 k_2}{m(k_1+k_2)}}\) B \(\sqrt{\dfrac{k_1+k_2}{m}}\) C \(\sqrt{\dfrac{k_1 k_2}{m}}\) D \(\sqrt{\dfrac{k_1-k_2}{m}}\) Q 10 In SHM, the kinetic energy equals the potential energy at what displacement from mean position? A \(A\) B \(\dfrac{A}{2}\) C \(\dfrac{A}{\sqrt{2}}\) D \(0\) Q 11 The number of times KE of a particle in SHM becomes maximum in one complete oscillation is: A 1 B 2 C 4 D 3 Q 12 A pendulum clock runs fast in summer and slow in winter. The correct reason is: A Air density changes with season B Thermal expansion increases \(L\) in summer, increasing \(T\); the clock runs slow in summer C Gravity changes with temperature D Amplitude increases in summer Part III Wave Motion & Progressive Waves Q 13 A transverse wave is described by \(y = A\sin(kx – \omega t)\). The wave speed is: A \(A\omega\) B \(\dfrac{k}{\omega}\) C \(\dfrac{\omega}{k}\) D \(\dfrac{\omega^2}{k}\) Q 14 The speed of a transverse wave in a stretched string depends on which pair of quantities? A Tension and amplitude B Tension and linear mass density C Frequency and amplitude D Wavelength and frequency only Q 15 Two waves of intensities \(I_1\) and \(I_2\) interfere. The ratio of maximum to minimum intensity when \(I_1 : I_2 = 4 : 1\) is: A 9 : 1 B 4 : 1 C 5 : 3 D 25 : 1 Q 16 The equation of a stationary wave is \(y = 2A\cos(kx)\sin(\omega t)\). The distance between two adjacent nodes is: A \(\lambda\) B \(\dfrac{\lambda}{4}\) C \(\dfrac{\lambda}{2}\) D \(2\lambda\) Q 17 A wave pulse travels from medium 1 to medium 2, where wave speed in medium 2 is greater. At the boundary, the reflected pulse will have: A Phase change of \(\pi\) B No phase change C Phase change of \(\pi/2\) D Phase change of \(2\pi\) Q 18 The power transmitted by a transverse wave on a string is proportional to: A \(A\omega\) B \(A^2\omega^2\) C \(A^2\omega\) D \(A\omega^2\) Part IV Sound Waves & Resonance Q 19 The speed of sound in an ideal gas is given by \(v = \sqrt{\dfrac{\gamma P}{\rho}}\). If the temperature is doubled at constant pressure, the speed of sound becomes: A \(\sqrt{2}\,v\) C \(2v\) C \(\dfrac{v}{\sqrt{2}}\) D \(4v\) Q 20 An open organ pipe of length \(L\) resonates at its fundamental frequency. If it is half-submerged in water (effectively becoming a closed pipe of length \(L/2\)), the fundamental frequency: A Doubles B Halves C Remains the same D Becomes four times Q 21 Two tuning forks of frequencies 256 Hz and 260 Hz are sounded together. The number of beats heard per second is: A 516 B 2 C 4 D 8 Q 22 In a closed organ pipe, the ratio of frequencies of the fundamental and second overtone is: A 1 : 3 B 1 : 2 C 1 : 5 D 1 : 4 Q 23 A sound wave of intensity \(I\) has a sound level of 40 dB. If the intensity is increased to \(100I\), the new sound level is: A 60 dB B 4000 dB C 80 dB D 140 dB Q 24 The displacement node in a standing sound wave corresponds to a: A Pressure node B Pressure antinode C Zero pressure variation D Maximum particle velocity Part V Doppler Effect, Superposition & Mixed Concepts Q 25 A source of sound moves toward a stationary observer with velocity \(v_s\).

IIT JEE Physics Practice Paper – Optics (Set 4) Instructions Total Questions: 30 | Marks: 4 each | No Negative Marking Q1. Refractive index is defined as: c/v v/c λ/v f/v Q2. Snell’s law is: n₁sinθ₁ = n₂sinθ₂ θ₁ = θ₂ n₁ = n₂ None Q3. Critical angle occurs when: Refraction angle = 90° Incident angle = 90° Both equal None Q4. Mirror formula is: 1/f = 1/v + 1/u v = u + f f = v/u None Q5. Power of lens is: 1/f f v/u None Q6. Unit of power of lens: Diopter Watt Joule Newton Q7. Total internal reflection occurs when: Denser to rarer medium Rarer to denser Same medium None Q8. Image formed by plane mirror is: Virtual and erect Real Inverted None Q9. Magnification of mirror is: -v/u v/u u/v None Q10. Dispersion of light is due to: Different refractive indices Same speed Reflection Absorption Q11. Speed of light is maximum in: Vacuum Water Glass Air Q12. Concave mirror focal length sign: Negative Positive Zero Infinite Q13. Convex mirror forms image: Virtual Real Both None Q14. Lens formula is: 1/f = 1/v – 1/u 1/f = 1/v + 1/u v = u + f None Q15. Optical fiber works on: Total internal reflection Reflection Refraction Diffraction Q16. Young’s double slit experiment proves: Wave nature of light Particle nature Energy conservation None Q17. Fringe width depends on: Wavelength Mass Charge None Q18. Diffraction occurs when: Aperture size comparable to wavelength Very large aperture No aperture None Q19. Polarization proves: Transverse nature of light Longitudinal nature Particle nature None Q20. Coherent sources have: Same frequency Different frequency Random phase None Q21. Brewster angle relates to: Polarization Diffraction Reflection None Q22. Optical path = n × distance distance 1/n None Q23. Convex lens produces real image when: Object beyond F At F Inside F None Q24. Interference maxima condition: Path difference = nλ (n+½)λ λ/2 None Q25. Diffraction pattern central maxima is: Brightest Dark Same None Q26. Wavefront is: Surface of constant phase Constant velocity Constant energy None Q27. Huygens principle explains: Wave propagation Particle motion Energy loss None Q28. Angular magnification depends on: Focal length Mass Charge None Q29. Telescope works on: Refraction Diffraction Polarization None Q30. Microscope magnification depends on: Focal length Velocity Charge None Submit Optics – IIT JEE Notes (Set 4) Refractive Index Definition Refractive index (n) is defined as the ratio of speed of light in vacuum to speed of light in a medium. Formula: n = c / v Key Insight Higher refractive index means light travels slower in that medium. Refraction and Snell’s Law Law n₁ sinθ₁ = n₂ sinθ₂ Important Points Light bends towards normal when entering denser medium and away from normal when entering rarer medium. Total Internal Reflection (TIR) Conditions 1. Light must travel from denser to rarer medium 2. Angle of incidence must be greater than critical angle Applications Optical fibers, diamond sparkle, mirage formation Mirror Formula and Magnification Formula 1/f = 1/v + 1/u Magnification m = -v/u Key Insight Negative magnification indicates inverted image. Lens Formula and Power Lens Formula 1/f = 1/v – 1/u Power of Lens P = 1/f (in meter) Unit Diopter (D) Image Formation by Lenses Convex Lens Forms real image when object is beyond focal point and virtual image when inside focal length. Concave Lens Always forms virtual, erect, and diminished image. Dispersion of Light Concept White light splits into colors due to different refractive indices for different wavelengths. Key Insight Violet deviates most, red deviates least. Interference of Light Condition Constructive interference: path difference = nλ Destructive interference: path difference = (2n+1)λ/2 Young’s Double Slit Experiment Demonstrates wave nature of light. Diffraction Concept Bending of light around edges or through small apertures. Key Insight Occurs when aperture size is comparable to wavelength. Polarization Concept Polarization proves that light is a transverse wave. Brewster’s Law tanθ = n Wavefront and Huygens Principle Wavefront A surface of constant phase. Huygens Principle Every point on a wavefront acts as a source of secondary wavelets. Optical Instruments Microscope Magnification depends on focal length of objective and eyepiece. Telescope Used for viewing distant objects, works on refraction or reflection. Important Exam Concepts Conceptual Traps Light speed changes but frequency remains constant during refraction. Magnetic field does not affect light path. JEE Strategy Focus on sign conventions, formulas, and diagram-based understanding. Practice numerical problems regularly.

IIT JEE Physics Magnetism and Electromagnetic Induction practice paper with 30 MCQs, answers, explanations and instant score. 30 Questions | 4 Marks Each | No Negative Marking Q1. Unit of magnetic field is: Tesla Weber Henry Ampere Q2. Magnetic force on moving charge is: qvB qE mv²/r IR Q3. Force on current carrying conductor is: BIL qvB IR V/L Q4. Direction of magnetic force is given by: Fleming’s Left Hand Rule Right Hand Rule Lenz Law Ohm’s Law Q5. Magnetic field due to straight wire depends on: Current Distance Both None Q6. Magnetic field at center of circular loop is: μ₀I/2R μ₀I/R μ₀I/4R μ₀IR Q7. Lorentz force depends on: Velocity Charge Magnetic field All Q8. Unit of magnetic flux is: Weber Tesla Henry Joule Q9. Faraday’s law states: emf ∝ flux emf ∝ rate of change of flux emf ∝ current emf ∝ resistance Q10. Lenz law is based on: Conservation of energy Newton law Ohm law Coulomb law Submit Magnetism & Electromagnetic Induction – IIT JEE Notes (Set 3) Magnetic Field Basics Definition A magnetic field is the region around a magnet or current-carrying conductor where magnetic force can be experienced by moving charges or magnetic materials. SI Unit The SI unit of magnetic field is Tesla (T). It is a vector quantity and has both magnitude and direction. Magnetic Force on Moving Charge Lorentz Force F = qvB sinθ The magnetic force depends on charge, velocity, magnetic field, and angle between velocity and field. Important Insight If velocity is parallel to magnetic field, force is zero. If perpendicular, force is maximum. Force on Current Carrying Conductor Formula F = BIL sinθ Where B is magnetic field, I is current, and L is length of conductor. Direction Rule Fleming’s Left Hand Rule gives the direction of force acting on the conductor. Magnetic Field Due to Current Straight Wire B ∝ I / r Magnetic field increases with current and decreases with distance from wire. Circular Loop B = μ₀I / 2R Magnetic field is strongest at the center of the loop. Magnetic Flux Definition Φ = B × A × cosθ Magnetic flux represents the number of magnetic field lines passing through a surface. Unit The SI unit of magnetic flux is Weber (Wb). Electromagnetic Induction (EMI) Faraday’s Law Induced emf is proportional to rate of change of magnetic flux. ε = – dΦ/dt Key Concept Faster change in flux produces larger induced emf. This is widely used in generators. Lenz’s Law Statement The direction of induced current opposes the cause producing it. Important Insight Lenz’s law is based on conservation of energy and prevents violation of energy principles. Induced Current Conditions Induced current is produced when there is a change in magnetic flux through a circuit. Methods to Change Flux Change magnetic field, change area, or change orientation of the loop. Self Inductance Definition Self inductance is the property of a coil to oppose change in current flowing through it. Formula ε = -L (dI/dt) Mutual Inductance Definition It is the property by which a change in current in one coil induces emf in another coil. Application Used in transformers and wireless energy transfer systems. Alternating Current Basics AC Current Current that changes direction periodically is called alternating current. Frequency In India, AC frequency is 50 Hz. Key Exam Concepts Conceptual Traps Magnetic force does no work as it is perpendicular to velocity. Electric field can do work but magnetic field cannot. JEE Strategy Focus on right-hand rules, formulas, and conceptual understanding. Practice numerical problems involving magnetic force and induction carefully.

IIT JEE Physics Electrostatics and Current Electricity practice test with 30 MCQs, solutions, and instant score. 30 Questions | 4 Marks Each | No Negative Marking Q1. SI unit of electric field is: N/C Volt Ohm Ampere Q2. Coulomb’s law force varies as: r 1/r 1/r² r² Q3. Electric field inside a conductor is: Zero Maximum Infinite Constant Q4. Potential difference is defined as: Work per charge Charge per work Energy per time Force per charge Q5. Capacitance unit is: Farad Ohm Volt Ampere Q6. Ohm’s law is: V = IR P = VI F = qE W = qV Q7. Resistance depends on: Length Area Material All of these Q8. Current is defined as: Charge/time Work/time Energy/time Voltage/time Submit Electrostatics & Current Electricity – IIT JEE Notes (Set 2) Electric Charge and Coulomb’s Law Basic Concept Electric charge is a fundamental property of matter. Charges can be positive or negative and interact through electrostatic forces. Like charges repel and unlike charges attract. Coulomb’s Law F = k × (q₁q₂ / r²) The electrostatic force is directly proportional to the product of charges and inversely proportional to the square of the distance between them. This inverse square law is very important for IIT JEE. Electric Field Definition E = F / q Electric field is the force experienced by a unit positive charge placed in the field. Important Points The unit of electric field is N/C. The direction of electric field is the direction of force on a positive charge. Inside a conductor, the electric field is zero due to redistribution of charges. Electric Potential and Potential Difference Electric Potential V = W / q Electric potential is the work done per unit charge in bringing a charge from infinity to a point. Potential Difference It is the difference in potential between two points and is responsible for the flow of current in a circuit. Capacitance Definition C = Q / V Capacitance is the ability of a conductor to store charge. Parallel Plate Capacitor C = ε₀A / d Capacitance increases with plate area and decreases with distance between plates. Electric Current Definition I = Q / t Electric current is the rate of flow of charge through a conductor. Key Concept Current is caused by drift of electrons under an electric field. Though electrons move randomly, an applied field creates a net motion. Ohm’s Law Formula V = IR It states that current is directly proportional to voltage for a conductor at constant temperature. Graph Insight The V-I graph for an ohmic conductor is a straight line, and its slope represents resistance. Resistance and Resistivity Formula R = ρL / A Resistance depends on length, area, and material of the conductor. Important Points Resistance increases with length and decreases with cross-sectional area. Resistivity is a material property and is independent of shape. Combination of Resistors Series Combination R = R₁ + R₂ + R₃ Same current flows through all resistors, and total resistance increases. Parallel Combination 1/R = 1/R₁ + 1/R₂ + 1/R₃ Voltage remains the same across resistors, and total resistance decreases. Electrical Power Formula P = VI = I²R = V²/R Electrical power is the rate at which electrical energy is consumed or converted. Important Insight Higher current or voltage increases power. These formulas are frequently used in numerical problems. Key Exam Concepts Conceptual Traps Electric field inside conductor is zero. Work done depends on angle between force and displacement. Resistance does not depend on current or voltage directly. JEE Strategy Focus on formulas, units, and conceptual clarity. Practice derivations and numerical problems regularly to strengthen understanding.