Electricity Flashcards
Define electric current and amperes. Describe how an ammeter is used in a circuit
Electric current= formed whenever charge flows from one spot to another. This flow of charge is made up of electrons moving along the wires.
Amperes= measures the amount of charge that flows through it every second.
Ampere in a current = the current is high if a lot of charge flows through it and low if only a small amount of charge is passed through the ammeter.
Define voltage in terms of a measure of the energy electrons have in passing around a circuit and its measure in volts. Describe how to connect a voltmeter in parallel
Voltage is high if electrons are supplied with a lot of energy or are losing lots of energy. Voltage is measured in volts.
Connecting a voltmeter in parallel; they are not part of the circuit but rather attach across the component being measured, piggy backing it
Explain the concept of resistance and how it depends on the material, length and thickness of the wire.
As electrons pass along wire their path is restricted by atoms that make up the wire- this is resistance.
A high resistance means it is difficult for an electron to pass through the material
Material= different materials have different resistance
Wire= doubling the length of wire doubles the number of obstacles, doubling its resistance
Thickness= more difficult for electrons to pass along thin wires than thick.
Define electrical conductor and insulator and give some examples
Electrical conductor= Materials that an electric current can pass through. It all depends on their resistance.
Metals; aluminium, copper, tungsten
Resistors= such high resistant materials can block electric current completely.
E.g. Of insulators are plastic, rubber, wood, glass and ceramics.
Discus ohms as the unit of resistance. Discus qualitatively the relationship between voltage current and resistance. Use ohms law.
If you change any of the above at least one of them will change.
Voltage= IR
If current remains the same , voltage and resistance increases
If voltage stays the same, resistance will increase and current will decrease.
Is supply voltage is increased then the current flowing around the circuit will also increase.
Problems with series circuits
- Globes cannot be controlled individually with a switch. A switch can either turn all on or off
- current stops if any of the circuits blow which breaks circuit causing all lights to go out which means it becomes extremely difficult to locate the faulty light.
- adding more globes to the circuit reduces how brightly they glow.
What is a series circuit
When all the components of the circuit are connected up one after another to form a single loop.
Describe parallel circuits and how they overcome problems with series circuits.
A parallel circuit has a number of branches, each branch having its own component. The current leaving the batter his split between two globes. If there are two globes each globe would relieve had the total current and a third if there was there lights.
Explain why parallel circuits are used in household wirings
Using a parallel circuit enables each light and power point to work at full power with each light and PowerPoint located on its own switch and branch. Allows everything to be controlled independently and supplies everything with the same amount of voltage.
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Describe combination circuits
Sometimes some components in a circuit are arranged in series and other components in parallel. Series that have both series and parallel circuits are called combination circuits.
