• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Electricity and magnetism

Extracts from this document...

Introduction

Electricity and magnetism

The charge is the amount of electricity in a circuit.

The symbol for charge is Q.

The unit for charge is coulombs.

A capacitor is a device that stores charge.

Charge = current x time.

  • Most materials fall into two groups: conductors and insulators.
  • A conductor allows electrons to flow through it.
  • An insulator is a barrier to electricity.
  • An insulator may act as a store of electricity known as static electricity.
  • There is a small third group called semi conductors - these are used in electronics.
  • The current is carried by ELECTRONS.
  • Metals contain a "sea" of free electrons (negatively charged) which flow through the metal.
  • This is what allows electric current to flow so well in all metals.
  • Electric current will only flow if there are charges which can move freely (electrons).
  • There are some things that you need to know for the exam about the difference between CONVENTIONAL and ELECTRICAL current.
  • CONVENTIONAL current flows from POSITIVE TO NEGATIVE.
  • ELECTRICAL current flows from NEGATIVE TO POSITIVE.
  • So electrons flow opposite to the flow of conventional current.

CURRENT - is the flow of electrons round the circuit.

VOLTAGE

...read more.

Middle

The bigger the resistance of a component, the bigger its share of voltage.

Static electricity

  • There are two types of charge: + positive and - negative.
  • An uncharged material has equal numbers of both so the material is balanced out.
  • Friction between materials caused an exchange of charges.
  • The negative charges move but positive stay where they are.
  • Once a material is charged it will attract materials with the opposite charge and repel materials that have the same charge.
  • An example of static electricity in industry is when painting cars. The car body is charged evenly and the paint is prayed on. The paint particles are attracted to the car and spread out because of the charge. This ensures the car is painted evenly.

Forces and motion

  • Forces are usually a push or a pull.
  • Forces are measured using a newtonmeter and the unit of force is Newtons.
  • Forces work in pairs - as you push down on a table the table pushes up with equal force.
  • When there is no change in velocity or shape of an object then the forces are balanced e.g. book on table
...read more.

Conclusion

Sun tanningVisable light. Human sightInfrared. Cooking (heat)Microwaves. CookingRadio waves. Communication

Light
The primary light colours are red blue and green. They can be mixed, as follows, to form secondary light colours:
red + green = yellow
red + blue = magenta
blue + green = cyan

By using a prism, white light can be separated into all the different (dispersion) colours that make up white light. These are (starting with long wavelength):
red, orange, yellow, green, blue, indigo, violet

Reflection:
The angle of incident always equals the angle of reflection. These are measured against the normal which is an imaginary straight line at a right angle to the mirror.

Refraction:
Refraction is the process that occurs when light travels from one material to another, it is either speed up or slowed down. This has an effect on the light and bends it. The denser the material, the slower the speed of light.

Sound
Sound waves are caused by vibrations in the air. They cannot travel through vacuums. The denser the material, the faster sound can travel.

Sound waves are reflected and this is heard by us as an echo. The echo is the sound being reflected - just like light reflected from a mirror.

Ultrasound has a very high frequency and we canv not hear it but bats use it to fly and it is also used to look inside the body.

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Fields & Forces section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Fields & Forces essays

  1. Peer reviewed

    Investigating the forces acting on a trolley on a ramp

    5 star(s)

    experiment were recorded in a table with two columns; distance from light gate measured in millimetres and time taken to pass through the light gate, measured in milliseconds. Without taking friction into account, it was possible to take a rough estimate of acceleration due to gravity and hence it was

  2. Peer reviewed

    Determination of the acceleration due to gravity (g)

    4 star(s)

    reading an instrument incorrectly or recording the wrong number. Errors may also occur because of the limit of precision of equipment involved. There are two variables measured in the experiment, they are height and time. So all the errors in the finding out g come from the error of measuring of height and time.

  1. Peer reviewed

    Energy and its uses

    3 star(s)

    1 Kj is equal to 1000 joules. Energy Interconversions 1. Electric motor drives pulley on line shaft to raise mass: A power supply unit (PSU) was used to supply electrical energy to a motor which converts the electrical energy to kinetic energy after some energy loss through electrical resistance and heat, the kinetic energy is then converted

  2. Investigating a factor affecting the voltage output of a transformer.

    * I will carry out the experiment on clear work surfaces, away from bench edges, and away from any water. Standardisation/Fair Test As well as keeping all the variables listed under 'Variables' constant (except for primary voltage of course), in particular the number of turns on the primary and secondary

  1. Objective To find the acceleration due to gravity by means of a simple ...

    Timing stops at the beginning of the third interruption, as the pendulum complete one full oscillation.

  2. Measuring The Constant g; The Acceleration Due To Gravity

    * Scissors - Simply to cut the string to the desired length. * Ruler - To measure the length of the string fairly precisely, to the nearest millimetre, as this is more than enough precision for this particular experiment. * Stopwatch - To time the period of the oscillations to

  1. charging a capacitor at a constant rate(C08)

    be more easily observed, the results of times will be more accurate. 5. Before every charging, we should set the variable resistor to maximum resistance. Otherwise, the current flowing through the circuit may be too large that will destroy the microammeter.

  2. To see how the number of coils on an electromagnet affect its strength.

    That is exactly what happened in my experiment. Figure 1.0 shows what the paper clips looked like before we picked them up We did not attach the paper clips together We tried the experiment several more times, winding the coils 5 times each to a total of 35 times.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work