GCSE Physics

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ghoran
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172732
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GCSE Physics
Updated:
2012-09-23 14:49:30
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Unit two part three currents electrical circuits Two
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  1. A caharged insulator can be discharged by 
    • Connecting it to the earth with a conductor . Charge then flows though the conductor . The rate of flow of electrical charge is called the current 
    • If the object is - charged the extra electrons are repelled to earth leaving the object neutral 
    • If the object is + charged the extra electrons atap attracted from earth leaving the object neutral 
  2. The earth is such a large object that this transfer of electrons doesn't 
    Affect its charge 
  3. Electrical charges can move easily move through some substances such as 
    Metals 
  4. Th diagram shows the location of charged atoms inside an insulated metal object when a - charged rod is brought near to it . The conduction electrons in the object moved from the left hand side of the object to the right hand side when the - charged rod was brought near the object 
    A) why did the charges rod cause the conduction electrons to move to the other end 
    B) why did the transfer of conduction electrons in the object make the one end positive and the other end negative 
    C) in terms of electron transfer , explain why the insulated object would become - overall if the rod touched the object
    • A) because like charges repell 
    • B) the positive end is because tare protons are left behind the - end is where all the electrons end up from repelling 
    • C) the - electrons from the rod will transfer onto the + side of the object
  5. If a build of charge become high enough a
    Spark may jump through an insulator like air , across a gap between the object and any earthed conductor . This may take the form of a spark
  6. Fast moving object cans build up large charges due to the ...... Of ..... ... . When a tanker lorry is refuelling a plane or racing car , they are always connected together by a ... ..... . A plane can build up a huge charge when flying through clouds . When it lands it may try to ...... By creating a ..... Which would jump between the plane and earth . The spark could ..... Any .... .... . To prevent this a ... Strip is first connected from the plane , down to the ground allowing the ..... Charge to .... Safely before the fuel tankers are  allowed to approach
    • Friction 
    • Air resistance 
    • Copper wire
    • Discharge 
    • Spark 
    • Ignite 
    • Fuel vapour 
    • Metal 
    • Electrostatic 
    • Discharge
  7. An electric charge can sometimes build up on a car when it is 
    Moving . When the cars stops a person stepping out of the car may feel a shock as the charge discharges through his/her hand as the door is closed 
  8. A peroson who has walked on a nylon carpet may build up a charge
    And may receive a shock when touching any metal object which is earthed . Modern carpets may be made conducting to prevent this
  9. A lightening conductor is usually attached to tall buildings . Explain why the lightening conductor is made of copper
    Copper is a good conductor of electricity . Charge in lightening will flow to earth throughhthe copper rather than through the insulator (building) as a spark which may explode and kill people in the building 
  10. Whta is electrical current 
    The flow of electrical charge 
  11. The size of electrical current is the r
    The rate of flow of electrical charge 
  12. The size of the current is given by 
    I = Q/T 
  13. I represents 
    Current 
  14. Q represents 
    Charge 
  15. T represents 
    Time 
  16. Current is measured in 
    A - Amps 
  17. Charge is measured in 
    C - Columbus 
  18. Time is measured in 
    S - seconds 
  19. A charge of 450 C flows through an electric fire in 5 seconds what is the current 
    • I = Q/T 
    • I = 450/5 
    • I = 90 A 
  20. How much charge flows through a 2A fire in 2 minutes 
    • I  = Q/T 
    • 2  = Q/60 
    • 2 * 60 = Q 
    • 120 = Q 
  21. How much charge flows through a 0.5 A bulb in 3 hours 
    • I = Q/T 
    • 0.5 = Q/3 * 60 * 60 = 10,800 
    • 0.5 * 10,800 = Q 
    • 5400 = Q 
  22. 1mA = 1 milliamp =
    • 0.001 A
    • 1 * 10 (-3)
  23. 1mC = 1 millicoulomb =
    • 0.001 C
    • 1 * 10 (-3) 
  24. Calculate the curren. If 300 mC flows in 0.5 seconds 
    • I = Q/T
    • I = 300 * 10 (-3) / 0.5
    • I = 0.6 A 
  25. Potential difference is a type of 
    Voltage 
  26. The potential difference between two points in an electrical circuit is the 
    Work done (energy transferred) per coulomb of charge that passes between points 
  27. V represents 
    Voltage/potential difference 
  28. W represents 
    Work/energy
  29. C represents 
    Charge 
  30. What is the unit of voltage/potential difference 
    V (volts) 
  31. What is the unit of work/energy 
    J (joules)
  32. How much energy is transferred in a resistor if a charge of 4 mC (4 millicolumbs) of charge flows when the voltage of the supply is 24 V
    • V = W/Q 
    • 24 = W/4 * 10 (-3) 
    • 24 * 4 * 10  (-3)
    • 0.096 J 
  33. What must the p.d. Of the supply of 24 J of energy needed to transfer 18 C of charge
    • V = W/Q
    • V = 24/18 
    • V = 1.3333333333333333333333333... V 
  34. If a 12 V batteryhis used and 4 J of electrical energy is converted to heat how much charged has flowed
    • V = W/Q 
    • 12 = 4/Q 
    • 12 Q = 4 
    • Q = 4/12 
    • Q = 0.33333333333333333333333... C

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