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Back to HOME > IGCSE PHYSICS > IGCSE PHYSICS REVISION =GENERAL RULES FOR DOING PHYSICS EXAM PAPERS=
 * 1) **Read** all of the parts of a question before answering it.
 * 2) Pay attention to the number of **marks** on offer (eg for 3 marks, you must say at least three things).
 * 3) 1 mark questions saying 'State' or 'Recall' require **short, simple** answers.
 * 4) Learn all **definitions** and formulas word-for-word.
 * 5) Give enough **detail** in your answers. State the obvious eg //a force is a push or a pull.//
 * 6) Show that you can use Physics **vocabulary** whenever you can.
 * 7) Note the action **words** in the question (and answer accordingly): //State; Explain; Complete; Describe; Use (the graph); Suggest; Evaluate//
 * 8) **Part questions** are usually on a single topic eg the answer to part (a) feeds into (b).
 * 9) Stay aware of the **time** (1 mark per minute). If you get stuck, **move on** and return if you have time at the end.
 * 10) Don't be afraid to physically act out the electromagnetism **hand rules** in the exam.
 * 11) Never leave a question **blank**. If nothing else, write down relevant formulas or definitions.
 * 12) As you finish a question, quickly **re-read** your answer to make sure it makes sense.
 * 13) Don't leave early. **Check** and re-check your answers.
 * 14) After the exam, don't waste time discussing your answers. **Look ahead** to the next paper.

Calculations: always show your working: there are many marks for this even if the answer is wrong. These are the stages: **Formula - Rearrange - Information - Substitute - Calculate - Answer - Unit**
 * Underline**: Show your final answer clearly **highlighting** or underlining.
 * Significant figures:** There are marks for getting this right. Every answer should be given to the correct number of sf (the same sf as the numbers given in the question). eg 5.2*9.8 = 51 (2 sf). It is a good idea to state the sf to show that you know about it.
 * Equations**: if you are asked to write one down, use words not just symbols.
 * Rounding**: if you are asked to show a quantity is 'approximately equal to' a given value, show the rounding step: eg 8.7A (rounded to 9A).
 * Prefixes**: convert units such as kN (kilo-newtons) and mA (milli-amperes) by multiplying or dividing by 1000.
 * Assumptions**: many formulas can only be used with particular assumptions eg //a fixed mass of gas// or //temperature is kept constant// etc.
 * Common-sense**: consider whether numerical answers make sense eg //a person of mass 5.0 or 500 kg is not likely.//

Graphs are often marked for the following features:
 * **Size** (more than 50% of the graph paper)
 * **Axis** (label quantity and unit; numbers evenly spaced)
 * **Plotting** (usually 2 marks for accuracy of points). Mark points with small dots.
 * **Line of best fit** (**don't** join the dots; **don't** force it through the origin; only draw a **straight** line if it looks straight; and if it **is** straight, use a ruler).
 * **Anomalies** can be identified as points far from the line of best fit.

Calculating **gradient**: actually draw the rise-run **triangle** (make it large). Use measurements of the triangle for the calculation, NOT values from the coordinates. A gradient has a **unit**.


 * Proportional** quantities: state that a relationship is proportional or **linear** if A = kB, but not if A = kB + C or if A = kB 2 . Example: "kinetic energy increases with velocity, but the KE-v graph is **non-linear** (KE is prop. to v squared)".


 * Questions about experimental skills**
 * Method**: describe all the steps in the right order.
 * Quantities**: give the number and unit (in a table, unit is in the heading).
 * Repeat** readings. The reasons for this are:
 * make the result more **reliable** (gives the same result each time);
 * to find a **mean** value;
 * to spot **anomalies**.
 * Scales**: read them with your eye level with the reading (avoid **parallax** error).
 * Zero error**: make sure the ruler or meter starts at zero.
 * Apparatus**: learn the names eg measuring cylinder; ray box; ticker-timer; air-track; stand and clamp etc

Hot objects must be carried with **insulating** handles. Fasten clamp **stands** to the bench. Protect **eyes** from stretched wires; liquids; flying objects. Electricity supplies should be **low voltage**. Mop up **water** if it is spilled. Avoid **damage** to apparatus (don't exceed limits for elasticity/ current/ temperature/ force etc).
 * Examples of Safety precautions**
 * Weights** must not fall on toes.
 * Labcoats** protect skin and clothes from chemicals and hot materials.
 * Radioactive** materials must be stored inside lead containers and handled with forceps.


 * Variables**
 * Independent** variable is the one which you **choose** to change. You can make decisions about the range and number of values. It should be the **leftmost** column in a table and the horizontal axis on a graph.
 * Dependent** variable is the one which you measure. This is the variable you **average** when there are repetitions.
 * Controlled** variables are the ones you keep constant to ensure a **fair test**.


 * Evaluating** conclusions
 * Precision** - this means how many significant figures are used in a measurement. (eg 0.25s has a precision of 0.01s). It can be useful to estimate the precision as a percentage of the reading (eg here it is 4%)
 * Accuracy** - this means how close to the true value the result is.
 * Reliability** - whether a result can be repeated.

For **oscillations**, measure several and divide to find **time period** which will reduce effect of reaction time. To improve precision you can use a **scale** with smaller divisions. Does the question require improvement in the **method** (same apparatus used differently) or **equipment** (same method, different instruments)?
 * Improvements**
 * Reaction time** - this can adversely affect measurements of time (add 0.1s). To reduce it, use **electronic** timing or measure **longer** times.
 * Repeat** measurement (consider if it is appropriate in each situation).

When explaining, give **reasons**. Use **labelled** diagrams if it helps you to explain something. Mention all of the relevant physics **vocabulary**. When explaining a quantity, consider the relevant formulas: eg //pressure// depends //force// exerted on an //area//. In questions about **kinetic theory**, talk about **particles**.
 * Explanations**

Use a **ruler and penci**l. Don't rush. Draw large and clearly. For magnetic fields, the lines must show the **direction**, form **complete loops** and NEVER cross nor touch. In light diagrams, draw the **normal** and arrows on the rays. Light travels **into** the eye. In electric circuits, show conventional **current**.
 * Diagrams**
 * == **Don't say** == || == **Do say** == ||
 * Renewable sources "can be used again and again" || They never run out ||
 * Energy is "lost" || It is transferred to heat/ the environment. ||
 * Gravity || Force of gravity, gravitational force //or// weight ||
 * Gravity for 'g' || Gravitational field strength ||
 * "Coils" of a solenoid || Turns ||
 * "More accurate" apparatus || More precise scale etc - give details ||
 * Particles in liquids and gases "vibrate" || They move freely, randomly. Only particles in solids vibrate. ||
 * Heat || Heat energy //or// thermal energy ||
 * Amperage || Electric current ||
 * Potential Energy || //**Gravitational**// or //**Elastic**// Potential Energy ||
 * Conduction, Conductor, Insulator || **//Thermal//** or //**Electrical**// Conduction, whichever is relevant ||