AP Inter Physics (BIEAP) flashcards

35 cards. Read the term and the definition here. The deck at the top of this page is optional.

Least count of vernier

The smallest measurement a vernier calliper can read, equal to one main scale division minus one vernier scale division, typically 0.1 mm when 10 vernier divisions span 9 main divisions.

Principle of homogeneity

Every term in a physically valid equation must have the same dimensions. It is used to check equation correctness and to derive relations, but cannot fix dimensionless numerical constants.

Dimensional formula of pressure

Pressure equals force divided by area, so its dimensional formula is [ML^-1T^-2]. Stress, Young's modulus and energy density share this same dimensional formula.

Significant figures rule

In multiplication and division the result carries the least number of significant figures among the inputs; in addition and subtraction it keeps the least number of decimal places.

Projectile maximum range

For a projectile launched over level ground with speed u, range R = u² sin2θ/g is greatest at θ = 45°, giving R_max = u²/g when air resistance is neglected.

Relative velocity

The velocity of body A as observed from body B equals v_A minus v_B as vectors. It explains river-boat crossing problems and rain-falling-slantwise observations.

Centripetal acceleration

In uniform circular motion the speed is constant but the direction changes, producing acceleration v²/r directed toward the centre, with no tangential acceleration component.

Slope of velocity-time graph

The gradient of a velocity-time graph gives instantaneous acceleration, while the area enclosed between the graph and the time axis gives displacement.

Newton's second law

The net external force on a body equals the rate of change of its linear momentum; for constant mass this reduces to F = ma, a vector equation.

Impulse-momentum theorem

Impulse is force multiplied by the time it acts, and equals the change in momentum. It explains why extending collision time reduces the average impact force.

Limiting static friction

The maximum static friction before sliding begins equals μs times the normal force. Once sliding starts, kinetic friction μkN acts, usually smaller in magnitude.

Banked road condition

For a curve of radius r banked at angle θ with no friction, the design speed satisfies v² = rg tanθ, so the normal force supplies the needed centripetal force.

Work-energy theorem

The net work done by all forces on a body equals the change in its kinetic energy, ½mv² - ½mu², whether the forces are conservative or not.

Coefficient of restitution

The ratio of relative speed of separation to relative speed of approach after a collision. It equals 1 for elastic and 0 for perfectly inelastic collisions.

Power in terms of velocity

Instantaneous power equals the dot product of force and velocity, P = F·v. For a constant force at constant speed it reduces to Fv cosθ.

Energy stored in a spring

The elastic potential energy of a spring stretched or compressed by x from natural length is ½kx², where k is the spring constant in newtons per metre.

Simple pendulum period

For small oscillations the period is T = 2π√(L/g), depending on length and local gravity but not on the bob mass or, to first order, the amplitude.

Condition for SHM

Motion is simple harmonic when acceleration is proportional to displacement from the mean position and directed opposite to it, written a = -ω²x.

Speed of wave on string

A transverse wave travels along a stretched string with speed v = √(T/μ), where T is tension and μ is mass per unit length of the string.

Beat frequency

When two sound waves of slightly different frequencies f1 and f2 superpose, the loudness rises and falls at the beat frequency |f1 - f2|.

Critical angle

The angle of incidence in the denser medium for which the refracted ray grazes the surface. It satisfies sin C = 1/n, and total internal reflection occurs beyond it.

Lens maker's formula

For a thin lens of refractive index n and radii R1, R2, the focal length satisfies 1/f = (n - 1)(1/R1 - 1/R2), linking material and shape to focal length.

Prism minimum deviation

At minimum deviation the ray passes symmetrically, so the refractive index is n = sin[(A + δm)/2] divided by sin(A/2), where A is the prism angle.

Magnifying power of telescope

For a telescope in normal adjustment the angular magnification equals the ratio of objective focal length to eyepiece focal length, f_o/f_e, with tube length f_o + f_e.

Gauss's law

The total electric flux through any closed surface equals the enclosed charge divided by ε0. It simplifies fields of symmetric charge distributions like spheres and sheets.

Capacitance of parallel plate

For a parallel plate capacitor with plate area A and separation d, capacitance is ε0A/d in vacuum; inserting a dielectric of constant K multiplies it by K.

Drift velocity

The average velocity electrons acquire along a conductor under an applied field, related to current by I = nAev_d, typically only fractions of a millimetre per second.

Wheatstone bridge balance

The bridge is balanced, with no current through the galvanometer, when the ratio of resistances in one branch equals that in the other: P/Q = R/S.

Lenz's law

The direction of an induced current is such that its magnetic effect opposes the change in magnetic flux that produced it, a consequence of energy conservation.

Motional EMF

A straight conductor of length l moving with speed v perpendicular to a magnetic field B develops an EMF equal to Bvl between its ends.

Photoelectric threshold frequency

The minimum frequency of incident light below which no photoelectrons are emitted from a metal surface, related to work function by φ0 = hf0.

de Broglie wavelength

Every moving particle has an associated wavelength λ = h/p, where p is momentum. It becomes measurable for electrons and confirms matter's wave nature.

Bohr quantisation condition

In the Bohr model the electron's angular momentum is restricted to integral multiples of h/2π, so mvr = nh/2π, producing discrete allowed orbits and energy levels.

Radioactive half-life

The time in which half the nuclei in a radioactive sample decay, related to the decay constant by T½ = 0.693/λ; it is independent of sample size.

Depletion region

The narrow zone at a p-n junction left without mobile charge carriers after diffusion, containing fixed ions and creating a barrier potential that opposes further diffusion.