CBSE, NEET/JEE Physics

Describe briefly how the concept of displacement current is explained through charging/discharging of a capacitor in an electric circuit.
How is displacement current produced between the plates of a parallel plate capacitor during charging?
Distinguish between displacement current and conduction current.
Show that the displacement current inside a capacitor is the same as the current charging it (AC source, plate area A, separation d).
Explain using Ampere–Maxwell law why current flows through a capacitor when being charged by a battery. Write the displacement current in terms of rate of change of electric flux.
Why does current not flow in steady state in a capacitor connected across a DC battery? Explain momentary current during charging/discharging.
Write Maxwell’s generalization of Ampere’s circuital law and show that i = ε₀ dΦE/dt during charging of capacitor.

ELECTROMAGNETIC WAVES

Production & Nature

How does an oscillating charge produce electromagnetic waves?
Sketch a schematic diagram depicting oscillating electric and magnetic fields of an EM wave propagating along +z direction.
How is the frequency of EM waves related to the frequency of the oscillating charge?
Directions of electric and magnetic field vectors relative to each other and propagation.
Express the velocity of propagation in terms of peak values of electric and magnetic fields.
Prove that average energy density of electric field equals that of magnetic field.
Show, by example, how EM waves carry energy and momentum.
Determine propagation and magnetic field directions for E = E₀ sin(ωt + kz).
Write two characteristics of electromagnetic waves.
Explain why a galvanometer shows momentary deflection during charging/discharging of a capacitor.
Explain production of microwaves and why their frequency matches resonant frequency of water molecules in ovens.
Name types of EM radiation for (i) cancer treatment, (ii) tanning, (iii) maintaining Earth’s warmth, and method of producing any one.
Case-based conceptual questions (brain tumor, values, radioisotopes, gamma-rays, treatment).

ELECTROMAGNETIC SPECTRUM

Waves & Applications

Why are infrared waves referred to as heat waves?
Name EM radiation also called heat waves.
Identify EM waves for (i) killing germs in water purifiers, (ii) eye surgery, (iii) radar systems; write one source and one use each.
Identify EM waves with minimum wavelength and minimum frequency; write one use of each.
Distinguish gamma rays and radio waves in origin and application.
Identify EM spectrum parts used in radar systems and eye surgery; write frequency ranges.
If Earth had no atmosphere, would surface temperature be higher or lower? Explain.
Explain how EM waves exert pressure on a surface.
Explain how microwave ovens heat food containing water molecules.
Arrange EM waves in ascending order of frequency: gamma rays, microwaves, infrared, ultraviolet.

MAGNETISM & MATTER

Fundamentals

State Gauss’s law in magnetism. How is it different from Gauss’s law in electrostatics and why?
Define magnetic dipole moment. Is it a scalar or vector quantity? Give its SI unit.
Derive an expression for the potential energy of a magnetic dipole in a uniform magnetic field at angle θ. When is it in stable and unstable equilibrium?
Show that a current-carrying solenoid behaves like a small bar magnet and compare its axial field with that of a bar magnet.
Explain the SHM of a freely suspended magnetic dipole in a uniform magnetic field and derive the time period T = 2π√(I/mB).
Deduce the expression for the magnetic dipole moment of an electron orbiting around the nucleus.

Magnetic Field Lines & Properties

Draw magnetic field lines due to a circular loop carrying current. Show it acts as a bar magnet with m = IA.
Write four important properties of magnetic field lines due to a bar magnet.
Why can’t two magnetic field lines intersect each other?
Why do magnetic field lines form continuous closed loops?
Depict the field-line pattern of a current-carrying solenoid. How do these lines differ from an electric dipole?

Magnetism in Materials

Define magnetising field, magnetic induction, intensity of magnetisation, magnetising field intensity, magnetic permeability, relative permeability, and magnetic susceptibility. Write relations among them.
Describe properties of diamagnetic, paramagnetic, and ferromagnetic substances.
Describe diamagnetism in superconducting metals.
Draw field lines when (i) diamagnetic, (ii) paramagnetic substances are placed in an external field. Which property distinguishes this behaviour?
Show diagrammatically field lines in paramagnetic and diamagnetic materials. Explain.
Explain the basic difference between atom and molecule of diamagnetic vs paramagnetic materials.
Why are elements with even atomic numbers more likely to be diamagnetic?
Distinguish paramagnetic vs diamagnetic, and diamagnetic vs ferromagnetic in terms of susceptibility and behaviour in non-uniform fields.

Comparisons & Applications

Distinguish properties of dia-, para-, and ferro-magnetic substances (susceptibility, permeability). Give one example for each.
Draw and explain modifications in field lines for Nickel, Antimony, and Aluminium in a uniform magnetic field.
Write three points of difference between para-, dia-, and ferro-magnetic materials with examples.
Define magnetic susceptibility. Name one element with positive and one with negative susceptibility. What does negative susceptibility signify?
Identify nature and susceptibility of materials given relative permeability or susceptibility values.
Draw modifications in magnetic field pattern for paramagnetic and diamagnetic bars placed in uniform field.
Explain behaviour of diamagnetic material when cooled and why paramagnetic sample shows greater magnetisation when cooled.
Discuss temperature dependence of susceptibility for dia-, para-, and ferromagnetic materials.
State Curie’s law and its modification for ferromagnetic substances.

WAVE OPTICS

Huygens’ Principle

Define wavefront. How is it different from a ray?
State Huygens’ principle.
Depict wavefront shape for light diverging from a point source.
Depict wavefront shape for light emerging from a convex lens with point source at focus.
Show how plane wavefront traverses through a convex lens and focuses.
Use Huygens’ construction to show plane wave reflection and verify law of reflection.
Use Huygens’ principle to obtain law of refraction from rarer to denser and denser to rarer medium.
Explain why reflected and refracted light have the same frequency.
Explain effect of decreased speed in denser medium on energy of light.

Interference of Waves

State conditions for coherent sources and why coherence is necessary for interference.
Show that resultant intensity of two coherent waves depends on phase difference. Obtain conditions for constructive and destructive interference.
In Young’s double slit experiment, explain formation of bright and dark fringes and factors affecting fringe width.
Explain effects on interference fringes when (i) slit separation decreased, (ii) width of source slit increased, (iii) monochromatic source replaced by white light.
Explain effect on fringe width if Young’s experiment is immersed in water.

Diffraction

Use Huygens’ principle to explain formation of diffraction pattern from a single slit.
Explain diffraction pattern formation using secondary wavelets on a screen.
Write three features distinguishing interference fringes and single slit diffraction pattern.
Explain why secondary maxima become weaker as order increases.
Explain effect of slit width, screen distance, and wavelength on angular width of central maximum.
Explain bright spot formation at center of shadow of a tiny circular obstacle.

ATOMS

Alpha Particle Scattering & Rutherford’s Nuclear Model

State assumptions of Rutherford model. Why cannot it account for atomic stability?
Draw Geiger–Marsden experiment setup and explain estimation of nuclear size.
Explain why few α-particles scatter at angles > 90°. Give two conclusions about atomic structure.
Write two limitations of Rutherford nuclear model.
Derive expression for total energy of electron in hydrogen atom. Explain significance of negative energy.

Bohr Model of Hydrogen Atom

Write two limitations of Rutherford model and explain Bohr's improvements.
State postulates of Bohr’s hydrogen atom model.
Write mathematical forms of three postulates of Bohr's theory.
Derive radius of nth orbit and Bohr’s radius.
Show circumference of nth orbit = n × de Broglie wavelength.
How is necessary centripetal force provided for electron?
Derive total energy expression; show K = –2U.
Derive speed and time period of electron in nth orbit. Show time period ∝ n³.
State Bohr postulate for emitted photon frequency. Derive expression for transition ni → nf.
Show radius ∝ n² and total energy ∝ 1/n².
Derive magnetic field at nucleus due to electron in ground state orbit.

Hydrogen Spectral Series

Identify shortest and longest wavelengths in Lyman, Balmer, Paschen, Brackett & Pfund series and spectral regions.
Maximum number of spectral lines emitted in third excited state.
Conditions for obtaining Hα line in emission spectrum.
Explain how electron transitions produce spectral series in hydrogen.

at October 02, 2025

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Saturday, September 6, 2025

Revision 1 Check List Physics

Physics Checklist

Physics Checklists

This checklist provides a comprehensive overview of key topics in physics, organized by chapter and subtopic.

Electric Field

Derivations

Derive an expression for the torque acting on an electric dipole held in a uniform electric field, when the axis of the dipole makes an angle θ with the field.
Derive the expression for the electric field at the surface of a charged conductor.
Deduce the expression for the net electric field at a point P due to a system of n charges.
Find the resultant electric field due to an electric dipole of dipole moment 2aq at a point on its equator.

Conceptual Understanding

Why do the electrostatic field lines not form closed loops?
Why do the electric field lines never cross each other?
What is the physical significance of lim q→0 in the expression E = lim q→0 (F/q)?
Draw the electric field lines of a point charge Q when (i) Q > 0, (ii) Q < 0.
Depict the electric field lines due to two positive charges kept a certain distance apart.
Trace the field lines between a point charge +Q and a conducting surface.
Analyze the behavior and field lines for two large metal plates P1 and P2 placed between equal and unlike point charges.
In which orientation is a dipole placed in a uniform electric field in (i) stable, (ii) unstable equilibrium?

Electric Dipole Moment

Define the term electric dipole moment. Is it scalar or vector?
Deduce an expression for the electric field at a point on the equatorial plane of an electric dipole.
Derive the expression for the electric field due to a dipole at a point on its axial line in terms of dipole moment p. Show that in the limit x >> a, E = 2p / (4πε₀r³).

Electric Flux & Gauss’s Theorem

Define electric flux. Write its SI units.
State and explain Gauss’s law in electrostatics.
Justify that Gauss’s law is true for any closed surface, no matter what its shape or size is.
Use Gauss’s law to prove that the electric field inside a uniformly charged spherical shell is zero.
Use Gauss’s law to derive the expression for the electric field due to a uniformly charged infinite plane sheet.
Use Gauss’s law to derive the expression for the electric field due to an infinitely long straight wire.
Use Gauss’s law to derive the expression for the electric field due to two parallel large sheets.
Use Gauss’s law to derive the expression for the electric field due to a uniformly charged thin spherical shell.
Show that the electric field at the surface of a charged conductor is given by E = σ/ε₀ n.
Explain why the electric flux due to a point charge is independent of the size and shape of the surface.

MOVING CHARGES & MAGNETISM

Magnetic Force, Motion in a Magnetic Field & Combined Fields

Write the vector expression for Lorentz force. What is the direction of the force?
Define one tesla using the expression for magnetic force on a moving charge.
Deduce the conditions for maximum and minimum magnetic force on a moving charge.
Show that no work is done by the magnetic force on a moving charge.
Show that a charged particle follows a circular path when entering a uniform magnetic field perpendicular to its velocity, and derive the expression for its radius.
Trace the trajectory of a particle with velocity components parallel and perpendicular to the field.
Deduce the expression for the cyclotron frequency and show that it is independent of velocity and energy.
Write the condition for a charged particle to move undeflected in crossed electric and magnetic fields.

Magnetic Field due to Current (Biot–Savart Law)

State Biot–Savart law in vector form.
Use Biot–Savart law to derive the expression for the magnetic field at the centre of a circular loop. Draw field lines.
Use Biot–Savart law to derive the magnetic field at the centre of a semicircular loop.
Use Biot–Savart law to derive the expression for the magnetic field on the axis of a circular current loop. Draw field lines.

Ampere’s Circuital Law & Solenoid

State Ampere’s circuital law in integral form.
Explain how Biot–Savart law leads to Ampere’s circuital law.
Derive the expression for the magnetic field inside and outside a long straight conductor.
Use Ampere’s law to derive the expression for the magnetic field inside a long solenoid. Draw the field lines.
Sketch the magnetic field lines for a finite solenoid. How are they different from the field lines of an electric dipole?
Find the net magnetic field inside and outside two coaxial solenoids carrying currents in opposite directions.

Force on Current-Carrying Conductors

Derive the expression for the force on a straight current-carrying conductor in a uniform magnetic field. State the rule for its direction and the conditions for maximum/minimum force.
Derive the expression for the force per unit length between two long parallel current-carrying conductors. Hence define one ampere.

Torque on Current Loop, Magnetic Dipole

Deduce the expression for the magnetic dipole moment of an electron in orbital motion around the nucleus.
Show that a current-carrying loop has magnetic dipole moment m = NIA.
Derive the expression for the torque on a rectangular current loop in a uniform magnetic field. Show that τ = m × B.

Moving Coil Galvanometer

State the principle of a moving coil galvanometer.
Draw a labelled diagram and explain the working of a moving coil galvanometer. What is the function of the radial magnetic field?
Derive the mathematical expression for converting a galvanometer into an ammeter using a shunt resistance.
Derive the expression for converting a galvanometer into a voltmeter using a series resistance.
Define current sensitivity. Explain why higher current sensitivity may not always mean higher voltage sensitivity.
State two factors on which the current sensitivity of a galvanometer depends.
Explain the purpose of a low torsional constant suspension wire, a shunt/series resistance, and a soft iron core.

Alternating Current

Pure Components (R, L, C)

Prove that an ideal capacitor in an a.c. circuit does not dissipate power.
Prove that an ideal inductor does not dissipate power in an a.c. circuit.
Show that in an a.c. circuit containing a pure inductor, the voltage is ahead of current by π/2 in phase.

Impedance & Phasor Diagrams

Derive an expression for the impedance of a series LR circuit.
Derive an expression for the impedance of a series LCR circuit. Draw the phasor diagram.
Using a phasor diagram, derive the relation for current in a series LCR circuit and obtain the phase angle.

Resonance & Quality Factor

State the condition for resonance to occur in a series LCR circuit and derive an expression for the resonant frequency.
Define the quality factor Q of a resonant circuit. Explain its significance.
Plot a graph showing variation of current with angular frequency for two different resistances. Explain which gives sharper resonance.

Power in AC Circuits

Derive an expression for the average power consumed in a series LCR circuit. Define power factor.
Define wattless current.
Explain why a low power factor implies large power loss for transmission.

Transformers

State the principle and working of a transformer. Derive expressions for secondary voltage and current.
Explain why a transformer cannot work with DC.
Mention and explain major energy losses in a transformer.
Explain why a step-up transformer does not violate conservation of energy.

Miscellaneous AC Concepts

Derive the relation between peak value and rms value of an alternating current.
Write the rms and average value of an alternating emf over a complete cycle.
Why is AC voltage preferred over DC voltage for power transmission?
Predict and justify the effect on a lamp's brightness when capacitance or frequency is reduced in an AC circuit with a capacitor.

RAY OPTICS

Reflection

Derive the mirror equation for a real image formed by a concave mirror.
Derive the magnification formula for the image formed by a mirror.
Using the mirror formula, explain why a convex mirror always produces a virtual image.
Define focal length. Show that for a concave mirror, f = R/2.
Use the mirror equation to explain image formation for various object positions.

Refraction at Plane Surfaces & Total Internal Reflection (TIR)

Explain why the bottom of a water tank appears raised.
Derive the relation between real depth, apparent depth, and refractive index.
Draw a ray diagram for a parallel-sided glass slab and derive the lateral shift.
Define total internal reflection and state its essential conditions.
Derive the relation between refractive index and critical angle.
Explain how total internal reflection is used for transmission of video signals through optical fibers.
Draw ray diagrams showing prisms using TIR to obtain inverted images by deviating rays through 90° and 180°.

Refraction at Spherical Surfaces & Lenses

Derive the mathematical relation for refraction at a convex spherical surface.
Derive the lens maker’s formula.
Derive the relation between object distance (u), image distance (v), and radius of curvature (R) for a convex spherical surface.

Combination of Lenses and Lens–Mirror Systems

Explain how to find the focal length of two convex lenses kept in contact.
Explain the effect on convergence/divergence when convex and concave lenses/mirrors are combined.
Draw ray diagrams to find the final image position for lens–lens and lens–mirror systems.

Prism

Draw a ray diagram showing refraction through a glass prism.
Deduce the expression for the refractive index of glass in terms of the prism angle and angle of minimum deviation.
Show that i + e = A + D for a ray passing through a prism.

Microscope

Explain the working of a simple microscope. Deduce the expression for magnification.
Draw a ray diagram for a compound microscope. Derive the expression for total magnification.
Define magnifying power and explain why the objective and eyepiece should have small focal lengths.

Telescope

Draw a labelled ray diagram of an astronomical telescope.
Define the magnifying power of a telescope and write the expression for it.
Draw ray diagrams showing refracting telescopes for final image at infinity and at the near point.
Discuss the main limitations of a refracting telescope and how they can be minimized in a reflecting telescope.
Draw a schematic diagram of a reflecting telescope (Cassegrain).

DUAL NATURE OF RADIATION AND MATTER – PHOTOELECTRIC EFFECT

Basic Concepts

Define stopping potential and threshold frequency.
Define intensity of radiation in the photon picture and give its SI unit.
Explain why photoelectric emission is not possible at all frequencies and why photoelectric current increases with intensity.
Explain the effect of frequency on stopping potential.
Compare two monochromatic beams (red and blue) of the same intensity.
Describe three experimentally observed features of the photoelectric effect.

Graphs and Plots

Sketch the variation of stopping potential with frequency for two photosensitive materials.
Draw a variation of photocurrent with collector plate potential for different frequencies but the same intensity.
Explain how saturation current, stopping potential, and photocurrent vary in a photocurrent vs anode potential plot.

Photoelectric Effect and Wave Theory

Discuss why wave theory of light cannot explain the photoelectric effect.
List three observed features of photoelectric effect not explained by wave theory.

Einstein’s Photoelectric Equation

Write Einstein’s photoelectric equation.
State three salient features of photoelectric effect explained by Einstein’s equation.
Explain how cut-off voltage and threshold frequency can be determined using a suitable graph.
Draw a graph between frequency of incident radiation and maximum kinetic energy of emitted electrons. Explain how this graph is used to determine Planck’s constant and work function.
For a beam of monochromatic radiation, explain if the emitted photoelectrons have the same kinetic energy, if kinetic energy depends on intensity, and on what factors the number of emitted photoelectrons depends.

NUCLEI

Nuclear Size and Density

How is the size of a nucleus experimentally determined? Write the relation between the radius and mass number.
Show that the density of a nucleus is constant and independent of mass number A.

Isotopes, Isobars, and Nuclear Mass

Distinguish between isotopes and isobars, giving one example for each.
Why is the mass of a nucleus always less than the sum of the masses of its constituents?

Nuclear Forces

State the properties of nuclear forces.
Draw a graph showing the variation of potential energy between a pair of nucleons as a function of their separation.
Write two important conclusions you can draw regarding the nature of nuclear forces.

Binding Energy

Draw the graph showing the variation of binding energy per nucleon with the mass number.
What are the main inferences from the graph?
Explain the constancy of binding energy in the range 30 < A < 170 using the property that nuclear force is short-ranged.
Explain the release of energy in nuclear fission and fusion with the help of this plot.

Nuclear Reactions

Explain how mass is converted into energy in a nuclear reaction where both protons and neutrons are conserved.
Define mass defect and binding energy. Describe the fission process based on binding energy per nucleon.
Distinguish between the phenomena of nuclear fission and nuclear fusion.
Explain how energy is produced in stars, giving two examples of the nuclear reactions involved.