PHYSICS

PHYSICS

1. Electricity and Magnetism

   • Static Charge
     • Insulating materials can be charged by friction
     • Positive Charge +
     • Negative Charge -
       • Like charges repel
         • Unlike charges attract
     • Uncharged Body = Equal Number of positive and negative atoms
     • Like Charges Repel
     • Unlike Charges Attract
     • Uncharged body = equal number of negative and positive atoms
   • Current in Circuits
     • Measured by Ammeters
     • Current = Flow of Chagre
   • Magnetic Fields
     • Like poles repel, unlike poles attract
     • Magnetic Elements
       • IRON
       • COBALT
       • NICKEL
     • The earth has one! It goes approximately from North to South.
       • Due to this, a freely suspended magnet like in a compas will point North and South
   • Electromagnets
     • We can make an electromagnet stronger by doing these things:
       • Increasing the number of coils
       • Wrapping the coils around a (soft) iron core
       • Increasing the current
     • Current in a coil
     • Used in bells and relays

2. Forces and Motion

   • Force and Linear Motion
     • An elastic material will change shape when a force is applied to it. When removed it will return to its original shape. Elastic materials will have an elastic limit to which they can stretch.
     • Springs
       • Two springs hung in parallel = mass suspended on them halved, the extension will be halved
       • Two springs hung in series mean the mass applied will cause double the extension
     • s=d/t
     • An object will move if the forces are unbalanced
     • If the forces acting on an object are balanced it will stay still
     • Forces include, thrust, gravity, air resistance, friction and weight
   • Forces and Rotation
     • Forces can be used to turn an object round a pivot
     • moment (Nm) = force × distance
   • Forces and Pressure
     • Pressure (N/cm2) = Force (N) / Area (cm2)

3. The Solar System

   • 'Movement' of Sun and other stars caused by earth rotating
   • Nine planets orbit the Sun
   • Rotation of earth around its axis causes day and night
   • A lunar eclipse occurs when the Earth passes between the Moon and the Sun, and the Earth's shadow obscures the moon or a portion of it. A solar eclipse occurs when the Moon passes between the Earth and the Sun, blocking all or a portion of the Sun.
   • Gravitational forces determine the movement of planets around the sun
   • Weight (N) = Gravity (N/kg) acting on mass (kg)
   • Gravity = 10 N/kg

4. Energy Sources and Energy Transfer

   • Energy Resources
     • Energy Sources Include:
       • Biomass
       • Oil
       • Coal
       • Food
       • Wind
       • Waves
       • Solar
       • Natural Gas
       • Non-Renewable
       • Renewable
     • The Sun is the ultimate source of energy for most of the earth's energy resources e.g fossil fuels.
     • Fossil Fuels
       • Not unlimited, running out
       • Formed by dead matter being crushed under extreme pressure from sedimentary rock and heat from the mantle
         • Crude oil and gas = Dead marine and some land organisms
         • Coal = Dead plant materials
     • How energy is produced in a power station
       • 1.Heat is released from fuel and boils the water to make steam.
         • The steam turns the turbine and is the condensed back into water to be used again.
           • The turbine turns a generator and electricity is produced.
             • The electricity goes to the transformers to produce the correct voltage.
               • It is then transported through wires to be used at home and on an industrial scale
   • Conservation of Energy
     • Energy will flow from a body at high temperature to a body at low temperature
     • Energy can be transferred and stored
     • Different forms of energy include
       • Kinetic
       • Gravitational Potential
       • Strain/Spring
       • Chemical
       • Light
       • Sound
       • Heat
     • The laws of conservation states that energy cannot be created or destroyed, it changes from one form to another
       • Energy can dissipate, reducing its availability as a resource.