# Shared Flashcard Set

## Details

Electrical Energy in the Home
BOS Preliminary Physics, Topic 2 Revision
26
Physics
05/17/2014

Term
 How have the main sources of domestic energy changed over time? How has this affected society?
Definition
 Wood- Chem energy to heat&light energy. -> kept animals at bay, food cold be cooked, humans live in colder climatesDomesticated animals - Mech energy-> more food, + population, towns developed, animals must be upkeptWind and water - Mech energy-> expanded tradin, efficient production of food from grainCoal - Chem to light&heat-> steam engine, more alloys, industrial age, pollution, slums,finiteCoal gas - heat coal wout air-> streets safer at night, batman out of a jobElectric generator - coil rotated in magnetic fieldFuel burning power stations - burning fossil fuels turns turbine of electric generator -nuclear & hydro electric
Term
 How can electrical energy be distributed to remote locations?
Definition
 Using the electricity grid
Term
 How is electrical energy distributed?
Definition
 Transmission lines (and transformers to change the current and voltage to practical levels)
Term
 Describe the behaviour of electrostatic charges and the properties of the fields associated with them
Definition
Term
 Describe the behaviour of electrostatic charges and the properties of the fields associated with them
Definition
 Like charges repel, unlike charges attract. A body becomes charges when it gains or loses electrons. The direction of an electric field is the direction of the force on a positive charge
Term
 What is the SI unit of electric charge?
Definition
 The coulomb.It is equal to the charge on 6.25x10^18 electrons
Term
 What is an electric field?
Definition
 The field of force with a field strength equal to the force per unit charge at that pointE= F/q
Term
 What is electric current?
Definition
 The rate at which charge flows (coloumbs/sec OR amperes) under the influence of an electric field
Term
 What is the difference between AC and DC?
Definition
 AC = alternating current. The charge carriers move backwards and forwards periodically DC= Direct Current. The net flow of charge carriers moving in one direction
Term
 What is electric potential difference / voltage?
Definition
 The change in potential energy per unit charge moving from one point to the other(joules/coulomb OR volts)
Term
 How does potential difference change at different points around a DC circuit?
Definition
 The current loses electric potential energy as it passes through a resistor. The potential difference is not affected by the wires. The potential difference across the power supply is equal to the potential difference across the resistor
Term
 What is the difference between an insulator and a conductor?
Definition
 A conductor contains charge carriers. Charged particles are free to move through the materialAn insulator is a material which contains no charge carriers.
Term
 How can resistance be determined?
Definition
 Resistance is the ratio of voltage to current.R = V/I
Term
 How do the following factors affect the movement of electricity through a conductor:-length-cross-sectional area-temperature-material
Definition
 length- R1/R2 = l1/l2C-s A- R1/R2 = A2/A1 (inversely prop.)Temp - Increased temp = increased RMaterial - Ag = 0.94 x10^-2 Cu = 1 " " Al = 1.6 " " Fe = 5.7 " "
Term
 What is the difference between a series and a parallel circuit?
Definition
 When resistors are connected in series, the same current passes through each resistorWhen resistors are connected in parallel, the current divides and passes partly trough each resistor.
Term
 What are the uses of ammeters and voltmeters? Why are they connected differently?
Definition
 An ammeter measures current. It must be connected in series.A voltmeter measures potential difference across components of a circuit. To do this it must be connected in parallel with the component
Term
 Why are there different circuits for lighting, heating and other appliances in a house?
Definition
 To avoid overloading electrical wiring, to avoid short circuits, so that if one stops working they don't all stop.
Term
 What is power?
Definition
 The rate at which energy is transformed from one form to another
Term
 What is the relationship between power, potential difference and current?
Definition
 P=VIPower = Volts X Current
Term
 How can you calculate the total amount of energy used?
Definition
 The amount of energy used depends on the length of time the current is flowing and can be calculated used W = VItEnergy used = Volts X Current X time(s)
Term
 Why is the kilowatt-hour used to measure electrical energy instead of the joule?
Definition
 Because the amount of energy used by most devices is too large a number to be realistically used in joule form. KWH = energy transformed by a 1000W device in 1 hr. W = Pt =1000 X 3600 =3 600 000 J
Term
 How do different magnetic poles interact?
Definition
 Like poles repel, unlike poles attract
Term
 How do you determine the direction of a magnetic field?
Definition
 The direction of a magnetic field is the direction of force on a very small North pole when placed at that point
Term
 What is the direction of a magnetic field surrounding opposite charges?
Definition
 Magnetic field lines leave the north pole and enter the south pole
Term
 What is the right-hand grip rule?
Definition
 All electric currents are surrounded by a magnetic field. RHGR determines the direction of the magnetic field based on the direction of the current
Term
 How do solenoids and bar magnets produce magnetic fields?
Definition
 A solenoid is a wire that has been wound into a closely packed corkscrew shape. The magnetic field of a solenoid is similar to that of a bar magnet, except the current pass through the inside as parallel lines to form closed loops
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