The Daniell cell is a type of electrochemical cell invented in 1836 by John Frederic Daniell, a British chemist and meteorologist, and consisted of a copper pot filled with a ...copper sulfate solution, in which was immersed an unglazed earthenware container filled with sulfuric acid and a zinc electrode. He was searching for a way to eliminate the hydrogen bubble problem found in the voltaic pile, and his solution was to use a second electrolyte to consume the hydrogen produced by the first. Zinc sulfate may be substituted for the sulfuric acid. The Daniell cell was a great improvement over the existing technology used in the early days of battery development. A later variant of the Daniell cell called the gravity cell or crowfoot cell was invented in the 1860s by a Frenchman named Callaud and became a popular choice for electrical telegraphy. The Daniell cell is also the historical basis for the contemporary definition of the volt, which is the unit of electromotive force in the International System of Units. The definitions of electrical units that were proposed at the 1881 International Conference of Electricians were designed so that the electromotive force of the Daniell cell would be about 1.0 volts. With contemporary definitions, the standard potential of the Daniell cell at 25 °C is actually 1.10 V[+] Show More
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Daniell cell - Volt Defined
The Daniell cell is a type of electrochemical cell invented in 1836 by John ...
The Daniell cell is a type of electrochemical cell invented in 1836 by John Frederic Daniell, a British chemist and meteorologist, and consisted of a copper pot filled with a ...copper sulfate solution, in which was immersed an unglazed earthenware container filled with sulfuric acid and a zinc electrode. He was searching for a way to eliminate the hydrogen bubble problem found in the voltaic pile, and his solution was to use a second electrolyte to consume the hydrogen produced by the first. Zinc sulfate may be substituted for the sulfuric acid. The Daniell cell was a great improvement over the existing technology used in the early days of battery development. A later variant of the Daniell cell called the gravity cell or crowfoot cell was invented in the 1860s by a Frenchman named Callaud and became a popular choice for electrical telegraphy. The Daniell cell is also the historical basis for the contemporary definition of the volt, which is the unit of electromotive force in the International System of Units. The definitions of electrical units that were proposed at the 1881 International Conference of Electricians were designed so that the electromotive force of the Daniell cell would be about 1.0 volts. With contemporary definitions, the standard potential of the Daniell cell at 25 °C is actually 1.10 V[+] Show More
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Sci Eye Electricity S096LS44 S120LS44
Scientific Eye Series 10 (1997) Eight programmes from the broadcast ...
Scientific Eye Series 10 (1997)
Eight programmes from the broadcast schools' science series, each of which examines a single topic, with individual stories being used to illustrate more general scientific ideas. ...
The individual titles are: Safety; The Solar System; Air Forces; Electricity; Rust; Fire; Rocks; Limestone.[+] Show More
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Series and Parallel Circuits and Resistance
Series To calculate the total overall resistance of a number of resistors ...
Series To calculate the total overall resistance of a number of resistors connected in series you add up the individual resistances. This is done using the following formula: Rtotal = R1 ...+ R2 +R3 and so on. This means that more bulbs means more resistance and lower current as V = IR. In this case it would be V = I*3R
Parallel When you add bulbs in parallel the resistances add up differently. 1/Rtotal = 1/R1 + 1/R2 + 1/R3. This means that instead of the example above there the resistance tripled.
1/RT = 1/R + 1/R + 1/R .....
1/RT = 3/R
R total = R/3
So.... V = IR becomes V = IR/3 so the resistance of the circuit overall drops off
3V/R = I so the current will triple and the bulbs will appear much brighter.
This is the advantage of a parallel circuit in that you can keep adding bulbs without reducing the current flow. However, of course this will consume more power in the circuit. This is how most home lighting is configured.[+] Show More
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Static Electricity for GCSE plastic wrapper
This always happens when I open a mint from a plastic wrap. it acquires a ...
This always happens when I open a mint from a plastic wrap. it acquires a static charge from the friction then sticks to you by induction.
Amazing everyday Physics.
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Van De Graaf Electrical Current
This quick demo shows the idea of sparking and how fast the spark can move ...
This quick demo shows the idea of sparking and how fast the spark can move between the electrodes and also how to the frequency of spark changes due to lower ...air resistance as you get closer to to he dome.[+] Show More
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Van De Graaff - Amazing
Simple idea about how like charges repel from each other. The dome acquires ...
Simple idea about how like charges repel from each other.
The dome acquires a static charge with nowhere to go. It pushes onto the foil cups and they all feel repelled ...as there is nothing holding them together so the electrostatic produces a resultant force.
Electrostatic by a mechanical to Kinetic[+] Show More
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Electrostatic Rods Magic Attraction
This is a simple practical where you charge the two rods by friction then ...
This is a simple practical where you charge the two rods by friction then use the force generated by the electric field to overcome friction and pull one rod in ...a circle.
The glass is very low friction which clearly helps.
You can also do this with a paper sling on cotton and a clampstand[+] Show More
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Deadly Sparks - Wimshurst Machine and Leyden Jars - Electrocution?
The Wimshurst machine is an electrostatic generator. Its a machine for ...
The Wimshurst machine is an electrostatic generator.
Its a machine for generating high voltages or potential differences and developed between 1880 and 1883 by British inventor James Wimshurst
It has a ...distinctive appearance with two large contra-rotating discs mounted in a vertical plane and a spark gap formed by two metal spheres.
At the bottom you can see two Leyden jars or Leiden jars which are an electrical component which stores a high-voltage electric charge (from an external source) between electrical conductors on the inside and outside of a glass jar. It typically consists of a glass jar with metal foil cemented to the inside and the outside surfaces, and a metal terminal projecting vertically through the jar lid to make contact with the inner foil. It was the original form of the capacitor and in this case attached to increase the amount of charges that can be held on the machine.
We can use it for electrostatic experiments like the van de graff generator. However, we must be very careful as the sparks are really quite powerful and to touch the machine without grounding it first will give you a very nasty shock.
PLEASE DON’T try this at home it will give you a really nasty shock much worse than a VDG[+] Show More
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