What do the Grade 12 Physics cards cover?

28 cards across 5 chapters of the national textbook: Fluid Mechanics, Electromagnetism, Basics of electronics and 2 more. You can take any chapter one card at a time on the page itself.

Do these help with the Grade 12 national exam?

Yes. Grade 12 sits a national exam, and these are the Physics rules and formulas it expects you to know. Past papers with a worked answer behind every question are on the same site, also free.

Where do these cards come from?

They are drafted from Grade 12 Physics, the Ministry of Education textbook for this grade. A second pass that cannot see the chapter then re-derives every formula, constant and table row, and anything it cannot confirm is held back instead of published.

Yes. Every card here is free to read and the printable sheet is free to download. Neither needs an account.

When was this last checked?

30 August 2026. Cards arrive chapter by chapter, and the line under each one says when that card was last read through.

Free short notes and revision cards

Grade 12 Physics

Grade 12 Physics on Temari has 28 revision cards, arranged by the chapters of the Ethiopian national curriculum. Every card says when the rule applies, what each symbol in it stands for, and the mistake students most often make with it. They are free to read and need no account.

28
Cards: 5
Chapters: 16
Formulas: 10
Reference tables: Grade 12 Physics
Textbook: Free
Price: 30 August 2026
Last checked

Download the sheet

Everything28Formula16Reference table10Common mistake2

Across the whole subject

Dimensions of mechanical quantitiesReference tableArea · Volume · Density · +20

Quantity	How it is defined	Dimensions	SI unit
Area	$l \times b$	$[\mathrm{L^{2}}]$	$\mathrm{m^{2}}$
Volume	$l \times b \times h$	$[\mathrm{L^{3}}]$	$\mathrm{m^{3}}$
Density	$m \div V$	$[\mathrm{M\,L^{-3}}]$	$\mathrm{kg\,m^{-3}}$
Velocity	$s \div t$	$[\mathrm{L\,T^{-1}}]$	$\mathrm{m\,s^{-1}}$
Acceleration	$\Delta v \div t$	$[\mathrm{L\,T^{-2}}]$	$\mathrm{m\,s^{-2}}$
Force	$m \times a$	$[\mathrm{M\,L\,T^{-2}}]$	$\mathrm{N}$
Momentum	$m \times v$	$[\mathrm{M\,L\,T^{-1}}]$	$\mathrm{kg\,m\,s^{-1}}$
Impulse	$F \times t$	$[\mathrm{M\,L\,T^{-1}}]$	$\mathrm{N\,s}$
Work and energy	$F \times d$	$[\mathrm{M\,L^{2}\,T^{-2}}]$	$\mathrm{J}$
Power	$W \div t$	$[\mathrm{M\,L^{2}\,T^{-3}}]$	$\mathrm{W}$
Pressure and stress	$F \div A$	$[\mathrm{M\,L^{-1}\,T^{-2}}]$	$\mathrm{Pa}$
Young's modulus	$\sigma \div \epsilon$	$[\mathrm{M\,L^{-1}\,T^{-2}}]$	$\mathrm{Pa}$
Surface tension	$F \div l$	$[\mathrm{M\,T^{-2}}]$	$\mathrm{N\,m^{-1}}$
Coefficient of viscosity	$F \div (A \times \Delta v / \Delta x)$	$[\mathrm{M\,L^{-1}\,T^{-1}}]$	$\mathrm{Pa\,s}$
Angular displacement	$s \div r$	$[\mathrm{M^{0}L^{0}T^{0}}]$	$\mathrm{rad}$
Angular velocity	$\theta \div t$	$[\mathrm{T^{-1}}]$	$\mathrm{rad\,s^{-1}}$
Angular acceleration	$\omega \div t$	$[\mathrm{T^{-2}}]$	$\mathrm{rad\,s^{-2}}$
Torque	$F \times r$	$[\mathrm{M\,L^{2}\,T^{-2}}]$	$\mathrm{N\,m}$
Moment of inertia	$m \times r^{2}$	$[\mathrm{M\,L^{2}}]$	$\mathrm{kg\,m^{2}}$
Angular momentum	$I \times \omega$	$[\mathrm{M\,L^{2}\,T^{-1}}]$	$\mathrm{kg\,m^{2}\,s^{-1}}$
Gravitational constant	$Fr^{2} \div m_{1}m_{2}$	$[\mathrm{M^{-1}\,L^{3}\,T^{-2}}]$	$\mathrm{N\,m^{2}\,kg^{-2}}$
Spring constant	$F \div x$	$[\mathrm{M\,T^{-2}}]$	$\mathrm{N\,m^{-1}}$
Strain	$\Delta l \div l$	$[\mathrm{M^{0}L^{0}T^{0}}]$	none

When you use it

Use this table to check an equation before you trust it. Both sides of a correct physics equation always carry the same dimensions, so a mismatch tells you a mistake happened without you having to find it first.

Watch out

Equal dimensions do not make an equation correct. Dimensional analysis cannot see a missing half, a stray 2π or a wrong sign, because pure numbers have no dimensions at all. It rules equations out; it never rules them in.

Dimensions of heat quantitiesReference tableHeat and internal energy · Temperature · Specific heat capacity · +6

Quantity	How it is defined	Dimensions	SI unit
Heat and internal energy	$F \times d$	$[\mathrm{M\,L^{2}\,T^{-2}}]$	$\mathrm{J}$
Temperature	—	$[\Theta]$	$\mathrm{K}$
Specific heat capacity	$Q \div (m\,\Delta T)$	$[\mathrm{L^{2}\,T^{-2}\,\Theta^{-1}}]$	$\mathrm{J\,kg^{-1}\,K^{-1}}$
Latent heat	$Q \div m$	$[\mathrm{L^{2}\,T^{-2}}]$	$\mathrm{J\,kg^{-1}}$
Thermal conductivity	$QL \div (A\,\Delta T\,t)$	$[\mathrm{M\,L\,T^{-3}\,\Theta^{-1}}]$	$\mathrm{W\,m^{-1}\,K^{-1}}$
Entropy	$Q \div T$	$[\mathrm{M\,L^{2}\,T^{-2}\,\Theta^{-1}}]$	$\mathrm{J\,K^{-1}}$
Universal gas constant	$PV \div nT$	$[\mathrm{M\,L^{2}\,T^{-2}\,\Theta^{-1}\,N^{-1}}]$	$\mathrm{J\,mol^{-1}\,K^{-1}}$
Boltzmann constant	$R \div N_{A}$	$[\mathrm{M\,L^{2}\,T^{-2}\,\Theta^{-1}}]$	$\mathrm{J\,K^{-1}}$
Coefficient of linear expansion	$\Delta L \div (L\,\Delta T)$	$[\Theta^{-1}]$	$\mathrm{K^{-1}}$

When you use it

Reach for this whenever temperature appears in a formula. Θ is a base dimension of its own, and forgetting it is the most common way a thermal calculation goes wrong on paper after looking right in your head.

Watch out

Specific heat capacity carries no mass dimension, but heat capacity does. One is per kilogram and the other is for the whole object, so swapping them silently changes an answer by a factor of the mass.

Dimensions of electrical quantitiesReference tableElectric current · Electric charge · Potential difference · +10

Quantity	How it is defined	Dimensions	SI unit
Electric current	—	$[\mathrm{I}]$	$\mathrm{A}$
Electric charge	$I \times t$	$[\mathrm{I\,T}]$	$\mathrm{C}$
Potential difference	$W \div q$	$[\mathrm{M\,L^{2}\,T^{-3}\,I^{-1}}]$	$\mathrm{V}$
Resistance	$V \div I$	$[\mathrm{M\,L^{2}\,T^{-3}\,I^{-2}}]$	$\Omega$
Resistivity	$RA \div l$	$[\mathrm{M\,L^{3}\,T^{-3}\,I^{-2}}]$	$\Omega\,\mathrm{m}$
Conductance	$1 \div R$	$[\mathrm{M^{-1}\,L^{-2}\,T^{3}\,I^{2}}]$	$\mathrm{S}$
Capacitance	$q \div V$	$[\mathrm{M^{-1}\,L^{-2}\,T^{4}\,I^{2}}]$	$\mathrm{F}$
Electric field	$F \div q$	$[\mathrm{M\,L\,T^{-3}\,I^{-1}}]$	$\mathrm{N\,C^{-1}}$
Permittivity of free space	$q^{2} \div (4\pi F r^{2})$	$[\mathrm{M^{-1}\,L^{-3}\,T^{4}\,I^{2}}]$	$\mathrm{F\,m^{-1}}$
Magnetic flux	$V \times t$	$[\mathrm{M\,L^{2}\,T^{-2}\,I^{-1}}]$	$\mathrm{Wb}$
Magnetic flux density	$\Phi \div A$	$[\mathrm{M\,T^{-2}\,I^{-1}}]$	$\mathrm{T}$
Inductance	$\Phi \div I$	$[\mathrm{M\,L^{2}\,T^{-2}\,I^{-2}}]$	$\mathrm{H}$
Permeability of free space	$2\pi r B \div I$	$[\mathrm{M\,L\,T^{-2}\,I^{-2}}]$	$\mathrm{H\,m^{-1}}$

When you use it

Every electrical dimension on this list is built from current, because current is the base quantity and charge is not. Derive charge as current × time first, and the rest of the column follows without memorising anything.

Watch out

Resistance and resistivity differ by one power of length, and that is the direction students reverse most. Resistivity is a property of the material and never changes with the shape of the wire; resistance is a property of that particular wire.

Dimensions of wave and modern physics quantitiesReference tableFrequency · Wavelength · Wave number · +4

Quantity	How it is defined	Dimensions	SI unit
Frequency	$1 \div T$	$[\mathrm{T^{-1}}]$	$\mathrm{Hz}$
Wavelength	—	$[\mathrm{L}]$	$\mathrm{m}$
Wave number	$1 \div \lambda$	$[\mathrm{L^{-1}}]$	$\mathrm{m^{-1}}$
Intensity	$P \div A$	$[\mathrm{M\,T^{-3}}]$	$\mathrm{W\,m^{-2}}$
Planck's constant	$E \div f$	$[\mathrm{M\,L^{2}\,T^{-1}}]$	$\mathrm{J\,s}$
Work function	$h f_{0}$	$[\mathrm{M\,L^{2}\,T^{-2}}]$	$\mathrm{J}$
Decay constant	$1 \div t$	$[\mathrm{T^{-1}}]$	$\mathrm{s^{-1}}$

When you use it

This is the shortest of the four cards and the one entrance-exam questions reach for most, because Planck's constant and angular momentum share the dimensions of $[\mathrm{M\,L^{2}\,T^{-1}}]$ and examiners like asking why.

Watch out

Frequency and angular velocity both come out as $[\mathrm{T^{-1}}]$ , and so does the decay constant. Dimensions cannot tell those three apart, which is a useful reminder of what the method is actually for.

Unit 1

Inverse Square Law of Apparent BrightnessFormula

b \propto \frac{L}{d^2}

b \propto \frac{L}{d^2}

$b$: Apparent brightness $W\,m^{-2}$
$L$: True brightness or luminosity $W$
$d$: Distance to astronomical object $m$

When you use it

Use this to relate the apparent brightness of an astronomical body to its luminosity and distance.

Watch out

Apparent brightness decreases with the square of distance, not linearly.

Drafted from Grade 12 Physics, pages 2-24, then checked twice before it went up

Missile Propulsion and Flight ComparisonReference tableCruise missile · Ballistic missile

Missile Type	Propulsion	Trajectory	Governing Physics
Cruise missile	Jet-propelled throughout flight	Controlled path	Conservation of momentum
Ballistic missile	Rocket-powered in initial phase only	Arc trajectory	Newtonian mechanics and gravity

When you use it

Use this to contrast the flight phases, engines, and trajectories of cruise versus ballistic missiles.

Watch out

Ballistic missiles carry rocket engines that fire only in the initial launch phase, not throughout the flight.

Drafted from Grade 12 Physics, pages 2-24, then checked twice before it went up

Radar Range EquationFormula

R = \frac{c t}{2}

R = \frac{c t}{2}

$R$: Distance to target $m$
$c$: Speed of light $m\,s^{-1}$
$t$: Round trip travel time $s$

When you use it

Use this to calculate the distance between a radar station and a target from the time taken for the radio pulse to go and return.

Watch out

Always divide the total travel time by 2. The measured time covers the distance to the target and back.

Drafted from Grade 12 Physics, pages 2-24, then checked twice before it went up

Ultrasound Image Display RegionsReference tableAnechoic · Hypoechoic · Hyperechoic

Term	Image Appearance	Echo Property	Body Feature
Anechoic	Black	No sound reflected	Fluid-filled regions
Hypoechoic	Dark gray	Fewer sound reflections	Soft body tissues
Hyperechoic	Light gray	Many sound reflections	Dense structures

When you use it

Use this to identify and classify the different shade regions on a medical ultrasound monitor.

Watch out

Anechoic regions appear black because fluids reflect zero echo, not because sound is blocked.

Drafted from Grade 12 Physics, pages 2-24, then checked twice before it went up

Unit 2

Kepler Third Law and Orbital PeriodFormula

\frac{T^2}{r^3} = \frac{4\pi^2}{G M}

\frac{T^2}{r^3} = \frac{4\pi^2}{G M}

$T$: orbital period $s$
$r$: orbital radius $m$
$G$: universal gravitational constant $N\,m^2\,kg^{-2}$
$M$: mass of central body $kg$

When you use it

Use when relating the orbital period of a planet or satellite to its average orbital radius around a central mass.

Watch out

The mass M in the denominator is the mass of the central body being orbited, not the orbiting satellite.

Drafted from Grade 12 Physics, pages 25-68, then checked twice before it went up

Newton Law of Universal GravitationFormula

F_g = \frac{G m_1 m_2}{r^2}

F_g = \frac{G m_1 m_2}{r^2}

$F_g$: gravitational force $N$
$G$: universal gravitational constant $N\,m^2\,kg^{-2}$
$m_1$: mass of first object $kg$
$m_2$: mass of second object $kg$
$r$: distance between centers of mass $m$

When you use it

Use to compute the gravitational attraction force acting between any two bodies with mass.

Watch out

The separation distance r is measured between the centers of the bodies, not between their surfaces.

Drafted from Grade 12 Physics, pages 25-68, then checked twice before it went up

Projectile Motion RangeFormula

R = \frac{v_0^2 \sin 2\theta}{g}

R = \frac{v_0^2 \sin 2\theta}{g}

$R$: horizontal range $m$
$v_0$: initial velocity $m\,s^{-1}$
$\theta$: launch angle $rad$
$g$: acceleration due to gravity $m\,s^{-2}$

When you use it

Use when finding the horizontal range of a projectile launched from and landing on the same level ground.

Watch out

This equation applies only when the launch elevation and landing elevation are identical.

Drafted from Grade 12 Physics, pages 25-68, then checked twice before it went up

Rotational Kinematics AnalogyReference tablev_f = v_0 + a t · Δs = v_0 t + 1/2 a t^2 · v_f^2 = v_0^2 + 2 a Δs · +1

Linear motion	Rotational motion
$v_f = v_0 + a t$	$\omega_f = \omega_0 + \alpha t$
$\Delta s = v_0 t + \frac{1}{2} a t^2$	$\Delta\theta = \omega_0 t + \frac{1}{2}\alpha t^2$
$v_f^2 = v_0^2 + 2 a \Delta s$	$\omega_f^2 = \omega_0^2 + 2\alpha \Delta\theta$
$\Delta s = \frac{v_0 + v_f}{2} t$	$\Delta\theta = \frac{\omega_0 + \omega_f}{2} t$

When you use it

Use to solve rotational motion problems with constant angular acceleration by mapping directly from linear kinematics.

Watch out

All angular displacements must be converted to radians before substituting into these kinematic equations.

Drafted from Grade 12 Physics, pages 25-68, then checked twice before it went up

Torque and Angular AccelerationFormula

\tau = I \alpha

\tau = I \alpha

$\tau$: net torque $N\,m$
$I$: moment of inertia $kg\,m^2$
$\alpha$: angular acceleration $rad\,s^{-2}$

When you use it

Use to connect the net rotational force with rotational inertia and angular acceleration of a rigid body.

Watch out

Angular acceleration must always be in radians per second squared, never revolutions per second squared.

Drafted from Grade 12 Physics, pages 25-68, then checked twice before it went up

Fluid Mechanics

Absolute and Gauge Pressure RelationFormula

P_{\text{abs}} = P_{\text{atm}} + P_{\text{gage}}

P_{\text{abs}} = P_{\text{atm}} + P_{\text{gage}}

$P_{\text{abs}}$: absolute pressure $Pa$
$P_{\text{atm}}$: local atmospheric pressure $Pa$
$P_{\text{gage}}$: gauge pressure $Pa$

When you use it

Use to convert between pressure gauge readings and the true absolute pressure relative to complete vacuum.

Watch out

Pressure measuring gauges read zero at atmospheric pressure. Never substitute gauge pressure directly into the ideal gas equation without adding atmospheric pressure.

Drafted from Grade 12 Physics, pages 69-117, then checked twice before it went up

Archimedes Principle for Buoyant ForceFormula

F_B = \rho_{\text{fluid}} g V_{\text{disp}}

F_B = \rho_{\text{fluid}} g V_{\text{disp}}

$F_B$: buoyant force $N$
$\rho_{\text{fluid}}$: density of the surrounding fluid $kg\,m^{-3}$
$g$: acceleration due to gravity $m\,s^{-2}$
$V_{\text{disp}}$: volume of fluid displaced $m^3$

When you use it

Use to determine the upward buoyant force acting on any partially or completely submerged object in a fluid.

Watch out

Use the density of the fluid, not the density of the object, to calculate the buoyant force.

Drafted from Grade 12 Physics, pages 69-117, then checked twice before it went up

Floating Fraction of an ObjectFormula

\frac{V_{\text{disp}}}{V_{\text{obj}}} = \frac{\rho_{\text{obj}}}{\rho_{\text{fluid}}}

\frac{V_{\text{disp}}}{V_{\text{obj}}} = \frac{\rho_{\text{obj}}}{\rho_{\text{fluid}}}

$V_{\text{disp}}$: volume submerged in fluid $m^3$
$V_{\text{obj}}$: total volume of the object $m^3$
$\rho_{\text{obj}}$: density of the floating object $kg\,m^{-3}$
$\rho_{\text{fluid}}$: density of the fluid $kg\,m^{-3}$

When you use it

Use to calculate the fraction or percentage of a floating object submerged beneath the surface of a fluid.

Watch out

This equation applies only to floating objects in static equilibrium, where the object density is less than the fluid density.

Drafted from Grade 12 Physics, pages 69-117, then checked twice before it went up

Pascal Principle in Hydraulic SystemsFormula

\frac{F_1}{A_1} = \frac{F_2}{A_2}

\frac{F_1}{A_1} = \frac{F_2}{A_2}

$F_1$: force applied on input piston $N$
$A_1$: cross-sectional area of input piston $m^2$
$F_2$: force exerted on output piston $N$
$A_2$: cross-sectional area of output piston $m^2$

When you use it

Use when finding the force or piston area in hydraulic lifts, brakes, and presses where confined fluid transmits pressure equally.

Watch out

Make sure the areas A_1 and A_2 are in the same units before calculating. If diameters are given, use area proportional to diameter squared.

Drafted from Grade 12 Physics, pages 69-117, then checked twice before it went up

Variation of Pressure with DepthFormula

P = P_0 + \rho g h

P = P_0 + \rho g h

$P$: absolute pressure at depth h $Pa$
$P_0$: pressure at the fluid surface $Pa$
$\rho$: density of the fluid $kg\,m^{-3}$
$g$: acceleration due to gravity $m\,s^{-2}$
$h$: depth below the surface $m$

When you use it

Use to calculate total hydrostatic pressure at any depth below the open surface of a static liquid.

Watch out

Always add atmospheric pressure P_0 when asked for absolute pressure. If only gauge pressure is required, omit P_0.

Drafted from Grade 12 Physics, pages 69-117, then checked twice before it went up

Electromagnetism

Faraday Law of InductionFormula

\varepsilon = -N \frac{\Delta\Phi_B}{\Delta t}

\varepsilon = -N \frac{\Delta\Phi_B}{\Delta t}

$\varepsilon$: induced electromotive force $\text{V}$
$N$: number of turns in coil $1$
$\Delta\Phi_B$: change in magnetic flux $\text{Wb}$
$\Delta t$: change in time $\text{s}$

When you use it

Use to calculate the electromotive force induced in a coil by a changing magnetic flux.

Watch out

The negative sign represents Lenz law, indicating that the induced emf opposes the change in flux.

Drafted from Grade 12 Physics, pages 118-142, then checked twice before it went up

Magnetic Field of a Straight WireFormula

B = \frac{\mu_0 I}{2\pi r}

B = \frac{\mu_0 I}{2\pi r}

$B$: magnetic field $\text{T}$
$\mu_0$: permeability of free space $\text{T}\cdot\text{m}\cdot\text{A}^{-1}$
$I$: current $\text{A}$
$r$: distance from the wire $\text{m}$

When you use it

Use to calculate the magnetic field strength at a given distance from a long straight current-carrying wire.

Watch out

The distance r must be in meters, not centimeters or millimeters.

Drafted from Grade 12 Physics, pages 118-142, then checked twice before it went up

Magnetic FluxFormula

\Phi_B = B A \cos\theta

\Phi_B = B A \cos\theta

$\Phi_B$: magnetic flux $\text{Wb}$
$B$: magnetic field $\text{T}$
$A$: area $\text{m}^2$
$\theta$: angle between magnetic field and normal to the area $\text{degrees}$

When you use it

Use to determine the total magnetic flux passing through a surface placed in a magnetic field.

Watch out

The angle theta is between the magnetic field and the area normal vector, not the surface plane.

Drafted from Grade 12 Physics, pages 118-142, then checked twice before it went up

Surface Angle in Magnetic FluxCommon mistake

When you use it

Use when given the angle between the magnetic field and the surface of a loop rather than its normal line.

Watch out

If the problem gives an angle with the surface plane, you must use 90 minus that angle for theta in the flux equation.

Drafted from Grade 12 Physics, pages 118-142, then checked twice before it went up

Transformer Turns RatioFormula

\frac{N_p}{N_s} = \frac{V_p}{V_s}

\frac{N_p}{N_s} = \frac{V_p}{V_s}

$N_p$: primary coil turns $1$
$N_s$: secondary coil turns $1$
$V_p$: primary voltage $\text{V}$
$V_s$: secondary voltage $\text{V}$

When you use it

Use to relate primary and secondary voltages with the number of turns in an alternating current transformer.

Watch out

Transformers operate only with alternating current and cannot step up or step down direct current.

Drafted from Grade 12 Physics, pages 118-142, then checked twice before it went up

Basics of electronics

Extrinsic Semiconductor TypesReference tableN-type · P-type

Type	Dopant group	Dopant examples	Majority carrier	Minority carrier
N-type	Group V (pentavalent)	As, P, Sb, Bi	Electrons	Holes
P-type	Group III (trivalent)	B, Al, Ga, In	Holes	Electrons

When you use it

Use to distinguish between N-type and P-type semiconductors, their impurities, and their charge carriers.

Watch out

Doped semiconductors remain electrically neutral overall even though one carrier type outnumbers the other.

Drafted from Grade 12 Physics, page 143 onwards, then checked twice before it went up

Logic Gates SummaryReference tableOR · AND · NOT · +2

Gate	Logic operation	Output is 1 when	Universal gate
OR	Addition: $y = A + B$	At least one input is 1	No
AND	Multiplication: $y = A \cdot B$	All inputs are 1	No
NOT	Inversion: single input	Input is 0	No
NOR	Inverted OR	All inputs are 0	Yes
NAND	Inverted AND	At least one input is 0	Yes

When you use it

Use to evaluate Boolean logic operations and outputs for digital logic circuits.

Watch out

In Boolean logic addition, 1 + 1 equals 1, representing TRUE OR TRUE, not arithmetic 2.

Drafted from Grade 12 Physics, page 143 onwards, then checked twice before it went up

Transistor Biasing ConditionCommon mistake

When you use it

Use when determining the bias voltage polarities required across the junctions of a bipolar transistor for proper amplifier operation.

Watch out

The emitter-base junction must be forward biased and the collector-base junction must be reverse biased. Setting both junctions to forward bias is incorrect.

Drafted from Grade 12 Physics, page 143 onwards, then checked twice before it went up

Transistor Current and Current GainFormula

\beta = \frac{I_C}{I_B},\quad I_E = I_B + I_C

\beta = \frac{I_C}{I_B},\quad I_E = I_B + I_C

$\beta$: Current gain $dimensionless$
$I_C$: Collector current $A$
$I_B$: Base current $A$
$I_E$: Emitter current $A$

When you use it

Use when calculating terminal currents or common-emitter current amplification in a bipolar junction transistor.

Watch out

Base current is given in microamperes while collector and emitter currents are in milliamperes. Convert all currents to amperes before computing.

Drafted from Grade 12 Physics, page 143 onwards, then checked twice before it went up

Transistor Regions ComparisonReference tableEmitter · Base · Collector

Region	Doping level	Physical size	Function
Emitter	Heavily doped	Medium size	Supplies charge carriers
Base	Lightly doped	Very thin	Passes carriers to collector
Collector	Moderately doped	Largest size	Collects charge carriers

When you use it

Use to compare the doping levels, physical dimensions, and functions of the three regions of a bipolar junction transistor.

Watch out

The base is both the thinnest and the most lightly doped layer, while the collector is the largest in physical size.

Drafted from Grade 12 Physics, page 143 onwards, then checked twice before it went up

The papers these formulas are for

Real national exam questions from past years, with a worked answer for each one.

Open the past papers

The same subject in other years

An exam paper keeps asking for what the year below taught. Those cards are here too.

Your other Grade 12 subjects

Everything else in this year that has cards so far.

Questions students ask

What do the Grade 12 Physics cards cover?: 28 cards across 5 chapters of the national textbook: Fluid Mechanics, Electromagnetism, Basics of electronics and 2 more. You can take any chapter one card at a time on the page itself.
Do these help with the Grade 12 national exam?: Yes. Grade 12 sits a national exam, and these are the Physics rules and formulas it expects you to know. Past papers with a worked answer behind every question are on the same site, also free.
Where do these cards come from?: They are drafted from Grade 12 Physics, the Ministry of Education textbook for this grade. A second pass that cannot see the chapter then re-derives every formula, constant and table row, and anything it cannot confirm is held back instead of published.
Is this free?: Yes. Every card here is free to read and the printable sheet is free to download. Neither needs an account.
When was this last checked?: 30 August 2026. Cards arrive chapter by chapter, and the line under each one says when that card was last read through.

Revise, then test yourself

Temari turns these cards into practice questions and marks them as you go, with an AI tutor to explain anything that did not land.

Start free