As level physics. Flashcards
(22 cards)
What are the base SI units used in A-level Physics?
Kilogram (kg), metre (m), second (s), mole (mol), kelvin (K), ampere (A)
Candela (cd) is not required.
What are the standard SI prefixes and their values?
- T (10¹²)
- G (10⁹)
- M (10⁶)
- k (10³)
- c (10⁻²)
- m (10⁻³)
- μ (10⁻⁶)
- n (10⁻⁹)
- p (10⁻¹²)
- f (10⁻¹⁵)
These prefixes represent the powers of ten for metric units.
What types of errors affect physical measurements?
- Random errors: Cause scatter; reduced by repeats.
- Systematic errors: Consistent bias (e.g., calibration error).
- Uncertainty types: Absolute, fractional, and percentage.
Also includes representing uncertainty using error bars and combining uncertainties using propagation rules.
What is the significance of significant figures in uncertainty?
More significant figures imply higher precision. The uncertainty should be expressed with the same level of precision.
What are the constituents of an atom?
- Proton: +1e, ~1 u
- Neutron: 0, ~1 u
- Electron: –1e, ~0.0005 u
What is meant by specific charge?
Charge-to-mass ratio (C/kg). Calculated as total charge ÷ total mass of a nucleus or particle.
Describe the photoelectric effect and its equation.
When light above a threshold frequency hits a metal surface, electrons are emitted.
Equation: hf = ϕ + E_k_max, where ϕ is the work function.
What are hadrons and leptons?
- Hadrons: Feel strong nuclear force (e.g., protons, neutrons, mesons).
- Leptons: Do not feel strong force (e.g., electrons, muons, neutrinos).
Includes baryon and lepton number conservation.
What is quark content for key particles?
- Proton: uud
- Neutron: udd
- π⁺: uanti-d
- π⁻: danti-u
- Kaons include strange quarks (e.g., K⁺: uanti-s).
Define annihilation and pair production.
- Annihilation: Particle meets antiparticle → 2 gamma photons.
- Pair production: Gamma photon creates particle-antiparticle pair if E ≥ 2mc².
What are transverse and longitudinal waves?
- Transverse: Oscillations ⟂ direction of travel (e.g., EM waves).
- Longitudinal: Oscillations ∥ direction of travel (e.g., sound).
What is the principle of superposition and stationary waves?
When two waves meet, their displacements add. Stationary waves form from two coherent waves traveling in opposite directions.
What are key interference formulas?
- Young’s fringe spacing: w = λD/s
- Grating equation: d sin θ = nλ.
What are the equations for refraction and optical fibres?
Based on Snell’s law and total internal reflection:
* n = c/c_s
* n₁ sin θ₁ = n₂ sin θ₂
* sin θ_c = n₂/n₁.
Includes modal and material dispersion.
Define scalar and vector quantities with examples.
- Scalars: Magnitude only (e.g., speed, energy).
- Vectors: Magnitude and direction (e.g., velocity, force).
What is momentum and impulse?
- Momentum: p = mv
- Impulse: FΔt = Δp.
Conservation of momentum in closed systems.
What is Hooke’s Law and how is energy stored in a spring?
- Hooke’s Law: F = kΔL
- Energy: E = 1/2 FΔL or area under force-extension graph.
Define Young Modulus.
E = tensile stress/tensile strain = F/(AΔL).
Found via stress-strain graphs.
What are the key equations for current, voltage, and resistance?
- I = ΔQ/Δt
- V = W/Q
- R = V/I.
Ohm’s Law: V ∝ I for ohmic conductors.
Define resistivity and give its formula.
ρ = R(A/L).
Depends on material and temperature. Includes thermistors and superconductors.
What is a potential divider and its application?
A circuit using two resistors to produce a specific output voltage.
Used in sensors, such as light or temperature sensing.
What is EMF and internal resistance?
- EMF = V + Ir
- EMF: Total energy per unit charge.
- Internal resistance (r) causes terminal p.d. to drop under load.
