Schleswig-Holstein Abitur Physics flashcards

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

Centripetal acceleration

For uniform circular motion a_z = v²/r = ω²·r, directed toward the centre. It changes only the direction of velocity, not its magnitude, so no work is done.

Newton's second law

The resultant force on a body equals mass times acceleration, F_res = m·a. Force and acceleration are parallel; constant force gives constant acceleration, not constant velocity.

Conservation of momentum

In a system with no external net force the total momentum p = Σm·v stays constant. This holds in all collisions, elastic or inelastic, and in explosions.

Kepler's third law

For circular orbits the period satisfies T² ∝ r³, since G·M/r² = 4π²·r/T². The constant depends only on the mass of the central body.

Elastic collision

A collision in which both momentum and kinetic energy are conserved. In inelastic collisions momentum is still conserved, but part of the kinetic energy becomes deformation, heat or sound.

Coulomb's law

The force between two point charges is F = (1/4πε₀)·q₁·q₂/r², attractive for opposite and repulsive for like charges. Doubling the distance reduces the force to one quarter.

Lorentz force

A charge q in fields E and B experiences F = q·(E + v×B). The magnetic part is perpendicular to velocity, does no work and only curves the path.

Radius in magnetic field

A charge moving perpendicular to a uniform B field follows a circle with r = m·v/(q·B). The period T = 2π·m/(q·B) does not depend on the speed.

Law of induction

The induced voltage equals the negative rate of change of magnetic flux: U_ind = −N·dΦ/dt. The minus sign is Lenz's law: the effect opposes its cause.

Lenz's law

The induced current is directed so that its magnetic field opposes the change of flux that produced it. This follows from energy conservation and explains braking effects.

Harmonic oscillator period

For a mass on a spring T = 2π·√(m/D); for a pendulum of length l, T = 2π·√(l/g) at small angles. The period is independent of amplitude.

Double-slit interference

Two coherent sources give maxima at path difference Δs = n·λ and minima at (n + ½)·λ. The fringe spacing on a distant screen is Δy = a·λ/d.

Diffraction grating

Many parallel slits produce sharp principal maxima at sin(θ_n) = n·λ/d. More slits sharpen the maxima, which allows precise wavelength measurement.

Total internal reflection

Light travelling from a denser to a less dense medium is fully reflected above the critical angle with sin(α_c) = n₂/n₁. This is the basis of optical fibres.

Standing wave condition

A string fixed at both ends supports wavelengths λ_n = 2l/n with frequencies f_n = n·f₁. Nodes are λ/2 apart and do not move; antinodes oscillate with maximum amplitude.

Photon energy

A photon carries E = h·f = h·c/λ, with h ≈ 6.626·10⁻³⁴ J·s. Higher frequency means more energy per photon; intensity means more photons per second.

Photoelectric equation

E_kin,max = h·f − W_A. Emission requires f above the threshold f_G = W_A/h; the maximum kinetic energy depends on frequency, not on intensity.

de Broglie wavelength

Every particle has wavelength λ = h/p = h/(m·v). Electron diffraction on crystals confirms this wave nature for matter.

Bohr energy levels

Hydrogen levels are E_n = −13.6 eV/n². A transition between levels emits or absorbs a photon with h·f = |E_n − E_m|, giving discrete spectral lines.

Half-life

The time after which half of the radioactive nuclei remain: T₁/₂ = ln2/λ. After n half-lives the remaining fraction is (½)^n; it does not depend on the initial amount.

Beta-minus decay

A neutron converts to a proton: n → p + e⁻ + ν̄. The mass number A stays the same, the atomic number Z increases by one, and an antineutrino is emitted.

Mass defect

The mass of a nucleus is less than the sum of its nucleons; Δm = Σm_nucleons − m_nucleus. The binding energy is Δm·c², about 931.5 MeV per atomic mass unit.

Binding energy per nucleon

The binding energy divided by the mass number A. It peaks near A ≈ 56, so fusion of light nuclei and fission of heavy nuclei both release energy.

Activity and becquerel

Activity A = λ·N is the number of decays per second, measured in becquerel (1 Bq = 1/s). It decreases exponentially with the same half-life as the number of nuclei.

Lorentz factor

γ = 1/√(1 − v²/c²), always at least 1. It grows strongly as v approaches c; at v = 0.8·c, γ ≈ 1.67.

Time dilation

A moving clock runs slow: Δt = γ·Δt₀, where Δt₀ is the proper time measured in the clock's rest frame. The effect is symmetric between inertial observers.

Length contraction

A moving object is shortened along its direction of motion: l = l₀/γ, where l₀ is the proper length in its rest frame. Perpendicular dimensions are unchanged.

Relativistic energy-momentum relation

E² = (p·c)² + (m·c²)². For a particle at rest E₀ = m·c²; for photons m = 0, so E = p·c.

Systematic error

A one-directional deviation caused by the apparatus or method, such as a zero offset or calibration fault. Repeating measurements does not reduce it; it requires correction or recalibration.

Linearising a graph

Transforming data so the expected relation becomes a straight line, e.g. T² against l for a pendulum. The slope then yields the constant and the intercept reveals systematic offsets.

Uncertainty of the mean

For n repeated measurements the mean has standard uncertainty s_x̄ = s/√n, where s is the standard deviation of the single measurements. More repeats increase precision.

Efficiency

Efficiency η = E_useful/E_input, often given in percent and always below 100 because losses occur as heat, sound or friction. It can be defined for each stage of an energy chain.