Hope this clears stuff up for you guys, happy to answer any further questions you have
(Original post by lyricalvibe)
Can someone clear this up please?I really don't know
If mains electricity is induces and it is AC, how is it transported to houses and such? Wouldn't the current just turn back and forth and never actually go anywhere as opposed to direct current which goes in one direction?
Ac doesn't mean that the current travels back and forth. Alternating current refers to the fact that the voltage is induced by rotating a magnet in a coil. As it rotates every half turn, the magnetic field changes and so as it rotates in one direction, the field constantly changes. This is what it means by alternating current.
The electricity still 'moves' in one direction through the wires
this is stepped up using a transformer to a very high voltage so that less electricity is wasted as heat as it travels through the wires. When it comes to our houses, it is given to us at 230volts. This has been stepped down due to a step down transformer.
(Original post by ed__)
Can anyone please help me with all the motor stuff and induction stuff on p5? I don't understand it one bit and still have all of p4 and p6 to do
I'm not at all screwed
. You will be have the best karma ever and i will worship you for the rest of my life, please help!!!!
The way a generator works is using electromagnetic induction. A magnet is rotated in a coil of wire which changes the magnetic field after every half turn. This induces a voltage, and possibly a current (in a complete circuit). Due to the voltage changing and so the current reversing as the magnet rotates, this is called alternating current (AC)
A motor uses the idea that a current carrying wire will experience a force when placed in a magnetic field. Essentially, a motor converts electrical energy to kinetic energy.
1) a coil of current carrying wire is placed in a magnetic field
2) this experiences a force
3) the force causes one side of the coil to be pushed upwards and the other pushed downwards
4),the coil is on a spindle and due to this motion, the coil rotates
5) every half turn, the split ring commutator reverses the current to ensure the motor keeps spinning in one direction
6) an axle can now be attached to the motor, it will spin as a result. This can be attached to a fan, wheels on an electric car etc.
(Original post by olmyster911)
Can someone explain resistance to me please?
I thought it meant the current was reduced which meant less electricity (?) so that with an LDR the resistance would be highest in day so the light was off, but it is the opposite to this. Why?
In an LDR, resistance falls in daylight. LDRs are present in street lamps and make the light switch ON when it is dark outside.
In bright light, the resistance is very little. As a result, the current does not do work on the component (bulb). Energy isn't supplied to the bulb, the current does no work and so the light doesn't switch on.
In the night, resistance is higher. As the current travels through, the current is made to do more work on the component. It transfers more energy and so the light switches.
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