Kerala Plus Two Physics (DHSE) flashcards

38 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 the distance between them, acting along the line joining them.

Electric flux

The number of electric field lines crossing a surface; numerically the surface integral of the electric field over that area, measured in volt-metres or newton-metre squared per coulomb.

Capacitance

The ratio of the charge stored on either conductor of a capacitor to the potential difference between them; measured in farads, where one farad equals one coulomb per volt.

Drift velocity

The small average velocity acquired by free electrons along a conductor under an applied electric field, typically of the order of a fraction of a millimetre per second.

Kirchhoff's junction rule

The algebraic sum of currents entering any junction of an electrical network is zero, expressing conservation of charge at that point of the circuit.

Internal resistance

The resistance offered by a cell or battery to current flowing through it, causing the terminal voltage to fall below the electromotive force when current is drawn.

Wheatstone bridge balance

The condition in which no current flows through the galvanometer connected across a four-resistance bridge, occurring when the ratio of the two arms on one side equals that on the other.

Ampere's circuital law

The line integral of the magnetic field around any closed path equals the permeability of free space multiplied by the total current enclosed by that path.

Lorentz force

The total force on a charge moving in electric and magnetic fields, equal to the electric force plus the magnetic force perpendicular to both velocity and field.

Magnetic dipole moment

A vector for a current loop whose magnitude is the product of current and area, pointing along the axis according to the right-hand rule; it determines the torque in a field.

Lenz's law

The induced current in a circuit always flows in a direction that opposes the change in magnetic flux that produced it, so mechanical work must be done to sustain induction.

Self-inductance

The property of a coil by which it opposes any change in the current through it, defined as the flux linkage per unit current and measured in henry.

Resonant frequency

The frequency of an alternating supply at which inductive and capacitive reactances are equal and cancel, making the impedance of a series circuit purely resistive and current maximum.

Power factor

The cosine of the phase angle between alternating voltage and current in a circuit; it equals resistance divided by impedance and determines the real power consumed.

Displacement current

A current equivalent to the rate of change of electric flux through a region, introduced by Maxwell so that Ampere's law holds during charging of a capacitor.

Total internal reflection

Complete reflection of light back into a denser medium when it strikes the boundary with a rarer medium at an angle exceeding the critical angle.

Fringe width

The separation between two consecutive bright or dark interference fringes in Young's double slit experiment, equal to wavelength times screen distance divided by slit separation.

Lens power

The reciprocal of the focal length of a lens measured in metres, expressed in dioptres; converging lenses have positive power and diverging lenses negative power.

Work function

The minimum energy required to eject an electron from the surface of a metal; it fixes the threshold frequency below which no photoelectric emission occurs.

Stopping potential

The negative potential applied to the collector that just prevents the fastest photoelectrons from reaching it, numerically equal to the maximum kinetic energy divided by electronic charge.

de Broglie wavelength

The wavelength associated with a moving particle, equal to Planck's constant divided by its momentum; it explains electron diffraction and is smaller for heavier or faster particles.

Bohr's quantisation condition

In a stationary orbit of the hydrogen atom, the angular momentum of the electron is an integral multiple of Planck's constant divided by two pi.

Half-life

The time in which half the nuclei of a radioactive sample decay; it equals the natural logarithm of two divided by the decay constant of the nuclide.

Binding energy per nucleon

The total mass defect energy of a nucleus divided by its mass number; it peaks near iron-56 and governs whether fission or fusion releases energy.

Depletion layer

The narrow region on either side of a p-n junction where mobile charge carriers have diffused away and recombined, leaving fixed ionised dopant atoms and an internal barrier field.

Zener breakdown

A reverse-bias phenomenon in heavily doped diodes where a strong junction field releases carriers, giving a nearly constant breakdown voltage used for voltage regulation.

Transistor current gain

In common-emitter configuration, the ratio of collector current to base current; a small base current controls a much larger collector current, enabling amplification.

Dimensional formula

An expression showing which base quantities and powers represent a physical quantity, used to check equation consistency and convert between unit systems.

Projectile range

The horizontal distance covered by a projectile launched and landing at the same level, equal to the square of the speed times the sine of twice the angle, divided by gravity.

Newton's second law

The rate of change of momentum of a body is proportional to the applied net force and takes place in the direction of that force; for constant mass it is force equals mass times acceleration.

Banking angle

The angle to which a road is tilted at a curve so that the horizontal component of the normal reaction supplies the centripetal force without relying on friction.

Escape speed

The minimum speed with which a body must be projected from a planet's surface to escape its gravitational field entirely, equal to the square root of twice the gravitational parameter over the radius.

Kepler's third law

The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit, the constant of proportionality depending on the central mass.

Bernoulli's principle

For steady, non-viscous, incompressible flow, the sum of pressure, kinetic energy per unit volume and potential energy per unit volume remains constant along a streamline.

Carnot efficiency

The maximum possible efficiency of a heat engine operating between two reservoirs, equal to one minus the ratio of sink temperature to source temperature on the Kelvin scale.

Simple harmonic motion

Oscillatory motion in which acceleration is proportional to displacement from the mean position and directed towards it, giving a sinusoidal variation of displacement with time.

Beat frequency

The rate at which loudness rises and falls when two sound waves of slightly different frequencies superpose, equal to the difference between the two frequencies.

Doppler effect

The apparent change in frequency of a wave due to relative motion between source and observer; frequency rises when they approach and falls when they recede.