Learning path: Batteries

Your path

1. Chemical ReactionsDirect prerequisite

   A chemical reaction rearranges atoms: bonds in the starting substances (reactants) break and new bonds form, making new substances (products) with different properties. No atoms are created or destroyed, so mass is conserved and a chemical equation must balance. For a reaction to happen at all, particles must collide in the right orientation with at least the activation energy, which is why temperature changes reaction rates.

   Take the Chemical Reactions quiz

2. EnergyDirect prerequisite

   The capacity to do work, taking forms such as kinetic energy (associated with motion) and potential energy (associated with position or configuration, such as height in a gravitational field). The total energy of an isolated system is conserved: energy changes form but is never created or destroyed.

   Take the Energy quiz

3. ElectricityDirect prerequisite

   Electricity is the behaviour of electric charge, and an electric current is charge flowing round a complete circuit, measured in amperes. A battery's potential difference (voltage) pushes the current, resistance opposes it, and for many materials they are linked by Ohm's law, V = IR. Circuits transfer energy at a rate P = IV; resistors add in series and combine as reciprocals in parallel. Mains electricity can kill and is never used for experiments.

   Take the Electricity quiz

4. BatteriesYour goal

   A battery stores energy chemically and releases it as electricity: in each cell, a chemical reaction pushes electrons out of the negative electrode (anode), through the circuit, and into the positive electrode (cathode). Single-use (primary) cells cannot be recharged; rechargeable (secondary) cells use reversible reactions. Lithium-ion cells, honoured by the 2019 Nobel Prize in Chemistry, power phones and laptops; because their lithium ions move in and out of the electrodes without consuming them, they can be recharged hundreds of times.

   Take the Batteries quiz