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Practicals

Voltaic Pile
AKA: Coin Battery

Summary

A voltaic pile is made from coins and an electrolyte.

Operation

The first voltaic pile, invented by Alessandro Volta in 1800, was the first ever electrical battery. He piled up alternating copper discs and brine soaked fabric. When the end contacts were connected, a current flowed. This practical involves recreating the voltaic pile using copper coins and filter paper soaked in salt water.

Equipment typically required (per set):

  • 2p pieces
  • Circles of thick filter paper (same diameter as coins)
  • NaCl (salt) solution, saturated
  • Milli-ammeter
  • Connecting wires
  • 2x Crocodile clips
  • 2p sized aluminium foil pieces (x2)

The filter paper circles should be soaked in the salt solution until they cannot soak up any more. These will form the electrolyte.

The 2p pieces and filter paper circle should be stacked alternately. The more coins, the higher the current that will be produced.

At each end of the stack, attach an aluminium disc. These will act as the connection to the battery. To these, attach a connecting wire using a crocodile clip. The free ends of the wires should be connected to the milli-ammeter.

From a technician perspective, this practical is fairly straight forward, although the discs of filter paper and aluminium may need to be cut before the lesson. Take care when cutting metal foils as edges can be very sharp.

The salt solution should be made by adding as much salt (NaCl) as the water can take. Use a magnetic stirrer to mix the two thoroughly.

The filter paper needs to be the thicker type so it can absorb a large amount of the salt solution and retain it when under physical pressure in the stack. Felt discs can be used as an alternative to the filter paper.

Safety

 Caution

Wear eye protection.

The contents of this page are for information only. Please refer to CLEAPSS, SSERC or ASE safety advice and/or publications before undertaking any preparation, practical experiment or using any equipment featured on this site or any other.