Grade 12 Physics Year-End Exam Study Guide

Flashcards to assist in studying for the Grade 12 Physics Year-End Exam.

What is the date of the upcoming final exam for Physics?

Thursday, 22 May 2025

What is the total mark for the Physics exam?

40 marks

What are the sections on the test?

Section 1: Multiple-choice questions (MCQ) – 20 questions worth 1 mark each; Section 2: Longer questions (calculations + writing) – 7 questions worth 20 marks in total

List the topics that will be covered on the exam.

Capacitance; Electric current and resistance (Current (I) and Resistance (R), Ohm’s law); Electric Power; Electric circuits (Resistors in series and parallel, Complex circuits); Magnetism (Magnets, Electromagnetism, Magnetic force)

What is capacitance?

The ability of a conductor to store energy in the form of electrically separated charges.

What is the SI unit for capacitance?

Farad (F)

What is the relationship between capacitance, charge, and potential difference?

Capacitance is the ratio of charge to potential difference: 𝐶 = 𝑄/𝑉

What affects capacitance?

Size and shape of a conductor

What is the relationship between capacitance C and area A?

Directly proportional

What is the relationship between capacitance C and distance d?

Inversely proportional

What is a dielectric?

An insulating material placed between a capacitor's plates to increase capacitance.

What is the formula for electric potential energy stored in a capacitor?

𝑃𝐸electric = (1/2)QV = (1/2)CV^2

What is electric current?

The rate of flow of electric charge.

What is the symbol for electric current and its unit?

I, Ampere (A)

How do you measure electric current strength in a circuit?

With an ammeter.

What is the formula to calculate electric current?

I=Q/t

What is the direction of conventional current flow?

From a battery's positive pole to its negative pole.

What is the actual charge flow in metallic conductors?

Electrons carry negative charge from the negative side of a power supply around a circuit and back into the positive side, in the opposite direction to the conventional current.

What is resistance?

The opposition that an electrical device has to the flow of electrical current.

What is the symbol for resistance and its unit?

R, Ohm (Ω)

How is resistance defined?

As the ratio of potential difference to current.

What is Ohm's Law?

V=IR or 𝐼 = 𝑉/𝑅

What are ohmic materials?

Materials that have a constant resistance over a wide range of potential differences.

What are non-ohmic materials?

Materials that do not function according to Ohm's law.

List the factors that affect resistance in a conducting wire.

Length, Cross-sectional area (thickness), Temperature, Material

What are the sources of electric current?

Batteries

What is direct current (DC)?

Charges move only in one direction in the circuit.

What is alternating current (AC)?

In alternating current (ac), the terminals of the source of potential difference constantly change sign. The net motion of the charges isn’t only in one direction, but simply vibrate back and forth between the changing terminals.

Define electric power.

The rate at which work is done; 𝑃 = 𝑊/𝑡 = ∆𝑃𝐸/𝑡, measured in Watts (W)

Electric power formula

P = IV

What is equivalent resistance?

The total resistance of the resistors in series.

Calculate the equivalent resistance

𝑅𝑒𝑞 = 𝑅1 + 𝑅2 + 𝑅3 + 𝑅4 + 𝑅5

What is series circuits?

Series describes two or more components of a circuit that provide a single path for current.

What is parallel circuits?

Parallel describes a circuit arrangement where there are alternative pathways for current to flow.

How do you calculate the total resistance of resistors in parallel?

𝑅𝑒𝑞 = ( 1/𝑅1 + 1/𝑅2 + 1/𝑅3)−1

Define Magnetism

The property of some materials that allows them to give off an attractive or repulsive force.

Define Magnet

A material that gives off an external magnetic field, making it possible to apply a force over a distance.

Define Magnetic Field

A magnetic field is a region in which a magnetic force can be detected and is strongest at the poles.

Define Magnetic domains

A magnetic domain is a region composed of a group of atoms whose spins are aligned in the same direction:

What can create a magnetic field?

Moving electric charge (current)

What happens to a charge moving through a magnetic field?

It experiences a magnetic force.

What is the formula for magnetic force?

𝐹magnetic = q.v.B

What is the magnitude of the magnetic field B?

𝐵 = 𝐹𝑚𝑎𝑔𝑛𝑒𝑡𝑖𝑐/q.v

What is electrical energy conversion?

𝑃 = 𝐼^2R or 𝑃 = 𝑉^2/𝑅