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Physics (Theme 1:General Physics (Chapter 1: Measurement (Length, metre, m…

- - - - (weight of apple x perpendicular distance from apple to pivot) / ( weight of standard masses x perpendicular distance from masses to pivot)
  - - - Elastic potential energy
      - Gravitational potential energy
      - Chemical potential energy
    - - W = F x s, W = workdone by constand force, F = constand force, s = distance moved by the object in the direction of the force
      - K.E. = 1/2 m v2 , E= kinectic energy, v = speed of the body, m = mass of the body
      - E = mgh, E = gravitational potential energy , m= mass, g = gravitational field strength, h= height
    - - P= W/t = E/t , P = power, W= workdone, E= energy converted, t= time taken
      - SI unit of power is watt ( W)
- - - - Convection is the transfer of thermal energy by means of convection currents in a fluid (liquid or gas), due to a difference in density
        
        By means of convection currents in the fluid ( gas or liquid)
        
        Requires amedium
        
        Convection current forms due to changes in the density of the fluid
      - Radiation is the transfer of thermal energy in the form of electromagnetic waves such as infrared radiation without the aid of a medium
        
        Colour and texture of the surface affect the absorption and emission
        
        Does not require a medium
      - Conduction is transfer pf thermal energy through a medium without any flow of the medium
        
        non-metal poor conductor of heat (insulator)
        
        Metal good conductor of heat
        
        Requires a medium
  - - - Change in temperature ( related to kinetic energy)
      - Change in state of matter ( related to potential energy)
        
        Liquid to gas (Boiling or evaporation)
        
        Boiling occurs at a particular temperature, relatively fast, takes place throughout the liquid, bubble formed in the liquid, temperature remains constant and external thermal energy source needed
        
        Evaporation occurs at any temperature, relatively slow, take place only at the liquid surface, no bubble are formed in the liquid, temperature may change and external thermal energy source not needed
        
        Gas to liquid ( condensation)
        
        Solid to liquid (melting)
        
        Liquid to solid (solidification)
  - - - Attractive forces between particles are very strong
      - Particles vibrate about fixed position
      - Particles are closely packed
      - Fixed volumes and shapes
    - - Attractive forces between particles are moderately stong
      - Particles are slightly farther apart as compared to solids
      - Particles can move freely within the liquid
      - have fixed volumes, but take the shape of the container
    - - Particles are very far apart
      - Attractive forces between particles are negligible
      - Particles move randomly at high speeds
      - no fixed volume or shape and are highly compressible
- - - - Sin c = 1/n
    - - Applications: magnifying glass, projector, camera and spectacle lenses
- - - - V total = V1 + V2
      - R total = R1 + R2
    - - V total = V1 + V2
      - 1/R total = 1/R1 + 1/R2
  - - - Neutral wire (blue) completes the circuit by providing a return path to the supply for the current . It is usually at zero volts
      - Earth wire (Green and Yellow) is the low-resistance wire. It is usually connected to the metal casing of appliances
      - Live wire (brown) is connected to a high voltage and delivers Current to appliance. This is the wire to which Circuit breakers, fuses and switches are fitted
    - - Circuit breakers, fuses, correct placement of switches, earthing, three-pin plugs, double insulation
  - - - E = W/Q, E = e.m.f. of the electrical energy source (V), W = workdone , (J), Q= amount of charge ( C)
    - - V = W/Q, V = Potential difference or voltage across a component (V), W= work done (J) , Q = Amount of charge (C)
    - - R = V/I, R = resistance of the component (ohm) , V = p.d. across the component (V) ,I-current flowing through the component ( A)
  - - - Stroking
      - Electrical method using a direct current
    - - Hammering
      - Electrical method using an alternating current
      - Heating
  - - - directed towards a negative charge
      - directed away from a positive charge