Notes of a Stressed Student

Houses are supplied with AC voltage of 230 V rms, at a 50Hz frequency. This is the equivalent of 230 V of DC.  Frequency f is a measure of how many times per second an event happens, in hertz, Hz Period T is the amount of time one cycle or event takes, measured in seconds.  Active: connected to voltage supply Neutral: is connected to the neutral link at the switchboard. Earth: Connects the appliance to the earth, as a safety device.  Kilowatt-hour: the amount of energy transformed by a 1000W appliance when used for one hour. This number is used in calculating costs of electricity.  Fuse: A short length of conducting wire of strip of metal that melts when the current through it reaches a certain value, breaking the circuit. it is used as a safety mechanism to prevent a overwhelmed circuit.  Residual Current Device: a device that operates by making use of magnetic effects of a current to break a circuit in the event of an electrical fault.

Electric charge is conserved. At any point in a conductor, the amount of charge (electrons) flowing in, will equal the charge flowing out of the that point.  In a closed loop of circuit, the sum of voltage drops must equal the full voltage. Series and Parallel Circuits: When elements are connected in series, they are joined together in a line, one after the other, and the current has only one path to take. When connected in parallel, the elements are connected so the current can take more than one path.  RESISTORS Resistors in series - more means more resistance R total = R 1 + R 2 + R 3 ... Resistors in parallel - more means less resistance  Voltage Dividers: an example of resistors in series. It is used to divide or reduce a voltage to a value needed for a part of a circuit. It has an input and output voltage.  Transducers: devices that convert energy from one form to another. A type of transducer is known as a sensor, which creates a vari...

Electric Charge: a basic property of matter. It occurs in two states: positive + and negative - charge. Current (I) : the movement of charged particles from one place to another, measured in coulombs. It is the rate at which charge flows past a point in the circuit. Is measured in amps (A). An ammeter is used. charge = total charge divided by time taken Potential difference: the amount if energy potential in joules, lost by each coulomb of charge in a given part of a circuit. PotDif = work divided by charge Power: the rate of doing work, or the rate at which energy is transformed from one form to another.  Resistance (W):  is the ratio of potential difference across a component to the current flowing through it, it is measure in ohms. Res = PotDif divided by current To convert the electrical energy into other forms of energy, loads resist the movement of charge. One coulomb of charge is equal to 6.242 * 10^18 elementary charges. It is the measure of electri...

What is the significance of the 5th of November? It is the date that Guy Fawkes attempted to blow up the Houses of Parliament, London, in 1605. V then blows up Old Bailey on the same day. What does the quote 'People shouldn't be afraid of their  governments.  Governments should be afraid of their people', mean? Governments should work for the good of the people, to help them, and if they are corrupt or otherwise then they should "fear" the people as they people should have the power to overthrow them.  What are the main themes of the story? Freedom & anarchy, bigotry, revenge, are themes that are explored. Many symbols are also used, such as V/5... How does Evey transform during her imprisonment? Be specific with regards to why this happens. How does McTeigue visually represent this transformation? Evey loses her fear, as she begins to realise that she would rather protect her ideals than her physical body. Through the torture, she sees that one ...

Many of the properties of water link back to its structure and bonding.  The oxygen atom is covalently bonded to two hydrogen atoms, and has two non-bonding electron pairs. The oxygen has a higher electronegativity than the hydrogen, so these bonds are polar. This means that the oxygen has a partial negative charge, as the electrons are more strongly attracted to it, and the two hydrogen atoms will have a partial positive charge, as the electrons are drawn away from them. Water molecules are able to form hydrogen intermolecular bonds .  Group 16 Hydrides: Water is one of the Group 16 Hydrides (as oxygen is a group 16 element, and it is bonded to hydrogen, H 2 O) However, water defies many trends found in this group. Generally, the melt/boil point of these compounds increase going down the group, due to increased dispersion forces. Despite being the smallest hydride, it has high melting and boiling points. Properties of Water include: Relatively high melting/b...

Physical Changes: a change of state and do not create a new substance. Ice melting to water, to dry ice subliming to produce fog are physical changes. Chemical changes: a reaction where one or more substances is transformed into one or more new products. They are can be identified by observing: * A substance 'disapears' * A gas is given off (effervescence) * A solid is precipitated * A colour change occurs * A new odour is released * Light is given off Chemical Equations - used to represent a chemical reaction, showing reactants and products and their physical states. Catalysts and other agents can also be shown above the arrow between sides. Reactants ----> Products To Write a Chemical Equation: A General Guide 1. Write out reactants on the left and products on the right, often obtained from information given in a question, including states. 2. Change the little numbers at the bottom to balance the charges of each compound 3. Balance equation...

What is a totalitarian regime? It is a form of government that <theoretically> permits no individual freedom, and seeks to control all aspects of life by the authority of the government.  Two Examples: *Pol Pot (Saloth Sar) ruled Cambodia as Prime Minister between 1975 - 79. He was head of the Khmer Rouge who imposed severe hardships on the Cambodian people, with mass evacuations and the displacement and murder of millions through brutality and impoverishment. *Adolf Hitler, as the leader of the Nazi party, he held a totalitarian regime over Germany between 1933 - 45. 

Redox reactions occur when electrons are transferred from one substance to another. Occur in two opposite parts , which must both occur – Oxidation and Reduction OXIDATION IS LOSS REDUCTION IS GAIN – OILRIG Oxidation occurs when an oxidation agent causes reductant to lose electrons (oxidise) Reduction occurs when reductive agent causes oxidant to gain electrons (reduce) Reductant = reducing agent Oxidant = oxidising agent Conjugate redox pair is made up of two species that differ by a certain number of electrons.   Half Equations ·              Redox Reactions do not show electrons transferred. ·              Half equations consider the reactions separately, thus enabling electron transfer to be seen. For complex equations: 1. Balance all atoms in the half equation except hydrogen and oxygen 2. Balance oxygen by adding ...