PSEB SS Physics flashcards
PSEB SS Physics · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Coulomb's law
- The electrostatic force between two point charges is proportional to the product of the charges and inversely proportional to the square of their separation, directed along the joining line.
- Electric field
- Electric field at a point is the force per unit positive test charge placed there; for a point charge Q it equals kQ/r² radially outward for positive Q.
- Gauss's law
- The total electric flux through a closed surface equals the enclosed charge divided by ε0; it is used with symmetry to find fields of spheres, cylinders, and infinite planes.
- Capacitor energy
- The energy stored in a capacitor is half the product of capacitance and voltage squared, also equal to QV/2 or Q²/(2C).
- Drift velocity
- Drift velocity is the average velocity of charge carriers along a conductor under an electric field; it relates to current by I = nAev_d.
- Ohm's law
- For a metallic conductor at constant temperature, current is directly proportional to potential difference; V = IR, where R is resistance.
- Resistivity
- Resistivity is a material property equal to resistance times cross-sectional area divided by length; it depends on material and temperature, not conductor dimensions.
- Kirchhoff's rules
- The junction rule states that total current entering a junction equals total current leaving; the loop rule states that the sum of potential changes around a closed loop is zero.
- Magnetic Lorentz force
- A charge q moving with velocity v in magnetic field B experiences force qvB sinθ perpendicular to both v and B; magnetic force does no work.
- Ampere's law
- The line integral of magnetic field around a closed path equals μ0 times the net current enclosed; it gives fields for long wires, solenoids, and toroids.
- Magnetic dipole moment
- For a current loop, magnetic moment m has magnitude NIA and direction normal to the loop; torque is m×B and potential energy is −m·B.
- Ferromagnetism
- Ferromagnetic materials have aligned magnetic domains and are strongly attracted to magnets; above the Curie temperature they become paramagnetic.
- Faraday's law
- The induced emf in a circuit equals the negative rate of change of magnetic flux through it; the minus sign expresses Lenz's law.
- Self-inductance
- Self-inductance L relates induced emf to rate of change of current in the same coil: ε = −L dI/dt; energy stored is ½LI².
- AC impedance
- Impedance Z combines resistance and reactance: Z = √(R² + (X_L − X_C)²); it determines rms current V_rms/Z in a series AC circuit.
- Resonance frequency
- In a series LCR circuit, resonance occurs when inductive and capacitive reactances are equal, giving angular frequency ω0 = 1/√(LC) and maximum current.
- Displacement current
- Maxwell's displacement current equals ε0 times the rate of change of electric flux; it makes Ampere's law consistent for charging capacitors.
- Electromagnetic wave speed
- In vacuum, electromagnetic waves travel at c = 1/√(μ0ε0), about 3×10^8 m/s, with E and B perpendicular to propagation.
- Radiation pressure
- Electromagnetic radiation carries momentum U/c; when absorbed completely it exerts pressure I/c, and when reflected normally the pressure is about 2I/c.
- Lens maker's formula
- For a thin lens in air, 1/f = (n − 1)(1/R1 − 1/R2), where R1 and R2 are surface radii with sign convention.
- Total internal reflection
- When light travels from a denser to rarer medium at an angle greater than the critical angle, it is totally reflected; sin C = n2/n1.
- Young's double slit
- In Young's double-slit experiment, fringe width is β = λD/d, where D is slit-screen distance and d is slit separation.
- Malus's law
- For unpolarized light through a polarizer, intensity becomes half; through a second polarizer at angle θ, transmitted intensity is I0 cos²θ.
- Photoelectric equation
- Einstein's photoelectric equation is hν = φ + Kmax; emission occurs only when photon frequency exceeds the threshold ν0 = φ/h.
- de Broglie wavelength
- A particle of momentum p has matter wavelength λ = h/p; for an electron accelerated through V volts, λ is about 12.27/√V ångström.
- Stopping potential
- Stopping potential is the reverse potential that stops the fastest photoelectrons; eV0 equals maximum kinetic energy, independent of light intensity.
- Bohr energy levels
- For hydrogen-like atoms, En = −13.6 Z²/n² eV; transitions between levels emit or absorb photons with energy equal to the level difference.
- Half-life
- Half-life is the time in which half the radioactive nuclei decay; N = N0(1/2)^(t/T), and activity falls by the same factor.
- Mass defect
- Mass defect is the difference between the sum of constituent nucleon masses and the nucleus mass; multiplied by c², it gives nuclear binding energy.
- p-n junction depletion
- At a p-n junction, diffusion of carriers leaves a depletion region with an electric field that opposes further diffusion and creates a barrier potential.
- Transistor current gain
- For a transistor, β = IC/IB and α = IC/IE; β = α/(1 − α), with α slightly less than one in the active region.
- Zener diode
- A Zener diode is operated in reverse breakdown, where voltage stays nearly constant; it is used for voltage regulation and reference supplies.