Topic: Fundamentals of Circuits

2.01 use the following units: ampere (A), coulomb (C), joule (J), ohm (Ω), second (s), volt (V) and watt (W)

unit for:

current : Ampere (A)

charge : coulomb (C)

resistance : ohm (Ω)

time : second (s)

potential difference : volt (V)

power : watt (W)  

2.04 know and use the relationship between power, current and voltage: and apply the relationship to the selection of appropriate fuses

power (w) = current (A) x voltage (V) 

when looking at a circuit a component will be given a power and a voltage appropriate to run at then the current can be calculated so the rating of the fuse can be selected for slightly higher than that. 


2.05 use the relationship between energy transferred, current, voltage and time: E= I × V × T

Energy (J) = potential difference (V) x current (A) x Time (s) 

2.07 explain why a series or parallel circuit is more appropriate for particular applications, including domestic lighting

Advantages of parallel circuits:

  • Components (e.g. bulbs) may be switched on/off independently.
  • If one component breaks, current can still flow through the other parts of the circuit.
  • Bulbs maintain a similar brightness.

Advantages of series circuits:

  • Fewer wires, cheaper and easier to assemble.
  • Uses less power



2.08 understand how the current in a series circuit depends on the applied voltage and the number and nature of other components

Notes on current:

  • As voltage increases the current also increases.
  • In general, the more components in a circuit, the lower the current.

2.09 describe how current varies with voltage in wires, resistors, metal filament lamps and diodes, and how to investigate this experimentally

in the bellow diagram the red box could represent a wire, a bulb, a resistor or a diode. 

By changing the resistance of the variable resistor the graphs are reproduced. 

2.10 describe the qualitative effect of changing resistance on the current in a circuit

Since V = IR, as you increase the resistance in a circuit, the current will decrease.

2.11 describe the qualitative variation of resistance of light-dependent resistors (LDRs) with illumination and thermistors with temperature


As illumination increases, resistance decreases


As temperature increases, resistance decreases.

2.12 know that lamps and LEDs can be used to indicate the presence of a current in a circuit

A lamp can be added to a circuit to check for a current. If current is flowing, the lamp will light up.

2.13 know and use the relationship between voltage, current and resistance: V = I × R

Potential difference (V) = Current (A) x Resistance (Ω) 


2.14 know that current is the rate of flow of charge

current is rate of flow of charge so I=Q/t 


2.15 know and use the relationship between charge, current and time: Q = I × t

Charge (C) = Current (A) x Time (s)


2.16 know that electric current in solid metallic conductors is a flow of negatively charged electrons

Electrons are negatively charged and free to flow in a metal so carry charge

2.17 understand why current is conserved at a junction in a circuit

At a junction current ‘splits’ to take both paths.

It comes back together when the paths meet again.

I1 = I2 + I3 +I4

2.18 know that the voltage across two components connected in parallel is the same

VT = V1 = V2

2.19 calculate the currents, voltages and resistances of two resistive components connected in a series circuit

VT = V1 + V2

IT = I1 = I2

RT = R1 + R2


2.20 know that: voltage is the energy transferred per unit charge passed and the volt is a joule per coulomb

2.21 know and use the relationship between energy transferred, charge and voltage: E = Q × V

Energy Transferred (J) = charge (C) x Voltage (V) 

2.22 identify common materials which are electrical conductors or insulators, including metals and plastics

Conducting Materials:

  • Copper
  • Aluminium
  • Gold
  • Silver

Will conduct electricity

Insulating Materials:

  • Glass
  • Air
  • Plastic
  • Rubber
  • Wood

Will not conduct electricity

Select a set of flashcards to study:


     Skills and equipment

     Remove Flashcards

Section 1: Principles of chemistry

      a) States of matter

      b) Atoms

      c) Atomic structure

     d) Relative formula masses and molar volumes of gases

     e) Chemical formulae and chemical equations

     f) Ionic compounds

     g) Covalent substances

     h) Metallic crystals

     i) Electrolysis

 Section 2: Chemistry of the elements

     a) The Periodic Table

     b) Group 1 elements: lithium, sodium and potassium

     c) Group 7 elements: chlorine, bromine and iodine

     d) Oxygen and oxides

     e) Hydrogen and water

     f) Reactivity series

     g) Tests for ions and gases

Section 3: Organic chemistry

     a) Introduction

     b) Alkanes

     c) Alkenes

     d) Ethanol

Section 4: Physical chemistry

     a) Acids, alkalis and salts

     b) Energetics

     c) Rates of reaction

     d) Equilibria

Section 5: Chemistry in industry

     a) Extraction and uses of metals

     b) Crude oil

     c) Synthetic polymers

     d) The industrial manufacture of chemicals

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