# GCSE Physics

 .remove_background_ad { border: 1px solid #555555; padding: .75em; margin: .75em; background-color: #e7e7e7; } .rmbg_image { max-height: 80px; } 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  The earth is such a large object that this transfer of electrons doesn't  Affect its charge  Electrical charges can move easily move through some substances such as  Metals  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 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 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 wireDischarge Spark Ignite Fuel vapour Metal Electrostatic Discharge 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  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 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  Whta is electrical current  The flow of electrical charge  The size of electrical current is the r The rate of flow of electrical charge  The size of the current is given by  I = Q/T  I represents  Current  Q represents  Charge  T represents  Time  Current is measured in  A - Amps  Charge is measured in  C - Columbus  Time is measured in  S - seconds  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  How much charge flows through a 2A fire in 2 minutes  I  = Q/T 2  = Q/60 2 * 60 = Q 120 = Q  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  1mA = 1 milliamp = 0.001 A1 * 10 (-3) 1mC = 1 millicoulomb = 0.001 C1 * 10 (-3)  Calculate the curren. If 300 mC flows in 0.5 seconds  I = Q/TI = 300 * 10 (-3) / 0.5I = 0.6 A  Potential difference is a type of  Voltage  The potential difference between two points in an electrical circuit is the  Work done (energy transferred) per coulomb of charge that passes between points  V represents  Voltage/potential difference  W represents  Work/energy C represents  Charge  What is the unit of voltage/potential difference  V (volts)  What is the unit of work/energy  J (joules) 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  What must the p.d. Of the supply of 24 J of energy needed to transfer 18 C of charge V = W/QV = 24/18 V = 1.3333333333333333333333333... V  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 .remove_background_ad { border: 1px solid #555555; padding: .75em; margin: .75em; background-color: #e7e7e7; } .rmbg_image { max-height: 80px; } Authorghoran ID172732 Card SetGCSE Physics DescriptionRevision Updated2012-09-23T18:49:30Z Show Answers