PhysicsQ&A by dot point

Define current as rate of flow of charge, $I = q/t$, state Ohm's law $R = V/I$, and apply the electrical power equations to calculate power and energy in a resistor.

Define the electric field as force per unit charge, $E = F_e/q$, describe the uniform field between parallel plates with $E = V/d$, and define electric potential difference as work per unit charge, $V = W/q$.

Describe electromagnetic induction as the production of an electromotive force by a changing magnetic field through a conductor, and explain how generators and transformers use induction.

Describe magnetic fields and the field produced by an electric current, apply $F_B = qvB$ to the force on a moving charge in a magnetic field, and explain the force on a current-carrying wire that underlies the electric motor.

Apply the rules for series and parallel circuits to current, voltage and total resistance, and analyze simple circuits to find the current through and voltage across each component.

Describe charging by friction, conduction and induction, state that charge is conserved and quantised in multiples of the elementary charge, and apply Coulomb's law $F_e = kq_1q_2/r^2$ to calculate the force between point charges.

Draw free-body diagrams showing all forces acting on an object, resolve forces into perpendicular components, and apply the equilibrium condition that the net force is zero in each direction.

Describe static and kinetic friction, apply $F_f = \mu F_N$ to calculate the friction force, and use the coefficient of friction to compare surfaces and decide whether an object slides.

State Newton's first law (the law of inertia), relate inertia to mass, and apply the law to objects at rest and moving at constant velocity, recognizing that balanced forces produce no change in motion.

State and apply Newton's second law, $F_{net} = ma$, to calculate net force, mass or acceleration, and analyze situations with several forces by finding the net force first.

State Newton's third law, identify action-reaction force pairs, and explain why the two forces in a pair act on different objects and therefore do not cancel.

Distinguish mass and weight, calculate weight using $F_g = mg$, and determine the normal force on an object on a surface, including on a horizontal surface and an incline.

Define displacement, velocity and acceleration as vector rates of change, distinguish them from distance and speed, and calculate average velocity and average acceleration from change in position and velocity over time.

Describe free fall as motion under the constant acceleration due to gravity, and apply the kinematic equations with $g = 9.81$ m/s squared to objects dropped, thrown down or thrown up near Earth's surface.

Interpret and sketch position-time, velocity-time and acceleration-time graphs, relating the slope of a graph to a rate of change and the area under a velocity-time graph to displacement.

Analyze projectile motion by treating the horizontal and vertical motions independently: constant horizontal velocity and vertical free fall, linked only by the common time of flight.

Apply the constant-acceleration kinematic equations to solve problems for displacement, initial and final velocity, acceleration and time, selecting the equation that omits the unknown not asked for.

Distinguish scalar and vector quantities, represent vectors as scaled arrows, and find the resultant of vectors by graphical and component methods, including resolving a vector into perpendicular components.

State the law of conservation of momentum, explain it using Newton's third law, and apply it to collisions and explosions where the total momentum before equals the total momentum after.

Define kinetic energy, gravitational potential energy and elastic potential energy, and apply the conservation of energy to systems with and without friction, recognizing friction transfers mechanical energy to internal (thermal) energy.

Define momentum as $p = mv$, define impulse as $F\Delta t$, and apply the impulse-momentum relationship $F\Delta t = \Delta p$ to calculate force, time or change in momentum.

Describe uniform circular motion, calculate centripetal acceleration with $a_c = v^2/r$ and centripetal force with $F_c = mv^2/r$, and identify the real force that supplies the centripetal force in a given situation.

State Newton's law of universal gravitation, apply $F_g = Gm_1m_2/r^2$ to calculate the gravitational force, and use the inverse-square relationship to reason about how the force changes with distance.

Define work as $W = Fd$ for a force along the displacement, relate work to the energy transferred, and define power as the rate of doing work, $P = W/t = Fv$.

State the mass-energy equivalence $E = mc^2$, describe the mass defect and binding energy of a nucleus, and outline nuclear fission and fusion as reactions that convert mass into energy.

Describe the Bohr model with quantised electron energy levels, explain how photons are emitted or absorbed when electrons change levels, and apply the energy-level relationship $E_{photon} = E_i - E_f$ for hydrogen.

Describe the dual (wave-particle) nature of light, define the photon and its energy $E_{photon} = hf$, and outline the photoelectric effect and the matter-wave (de Broglie) relationship $\lambda = h/mv$ as evidence for duality.

Describe the Standard Model classification of matter into quarks and leptons, use the quark composition of protons and neutrons, and read particle charges from the Standard Model chart on the Reference Tables.

Describe diffraction as the spreading of waves around obstacles and through openings, and explain interference as the superposition of waves, distinguishing constructive and destructive interference and standing waves.

State the law of reflection, define the absolute index of refraction $n = c/v$, and apply Snell's law $n_1\sin\theta_1 = n_2\sin\theta_2$ to refraction, including the bending of light between media.

Describe sound as a longitudinal mechanical wave needing a medium, relate pitch and loudness to frequency and amplitude, and explain the Doppler effect as an apparent change in frequency due to relative motion of source and observer.

Describe the electromagnetic spectrum as a family of transverse waves travelling at the speed of light in a vacuum, ordered by frequency and wavelength, and apply $c = f\lambda$ to electromagnetic waves.

Define amplitude, wavelength, frequency and period, distinguish transverse and longitudinal waves, and apply the wave equation $v = f\lambda$ and the period-frequency relationship $T = 1/f$.