# Equations & Symbols

If you are using Word to write your Lab Reports, we recommend you use MathType for the equations, which you can get on the University NPCS computers, or download it yourself online (the free version is sufficient for writing reports).

Equations may be included inline (i.e. as part of your regular text) if they are small and don't contain unusual symbols (e.g. square roots).

If you have a larger equation, or you want to number it to refer back to it later, you should have it on it's own line, centered on the column and it should have an equation number on the right.

#### Example

For example, the error propagation formula used in Circuits 1 is given by (1)

where R is the resistance, V is the voltage, I is the current across the resistor and α represents their associated uncertainties. Later on, you can refer to this as equation (1).

#### Rules

Some rules for equations:

• Define all variables in the text the first time that they appear, then make sure that you use the same symbol and font every time they re-appear.
• Remember to number all displayed equations, but do it differently to your references (e.g. Ref and equation (1))
• If you are using a reference for the equation then put the reference before or after in the regular text
• Equations should be read as part of the sentence and thus punctuated appropriately. Only capitalise the word following the equation if you have put a full stop after said equation.
• Use italics for variable names and upright for numbers, functions or abreviations e.g. Vsin(2wt)
• Make sure your equations are the same size font as the rest of your text.

# Units

Use SI Units unless something else is more appropriate.

#### Key Points

• Leave a space between the number and the unit, and use upright rather than italic font. "5 mm long" not "5mm long"
• Separate out individual units for clarity e.g. "10 m mK-1" not "10 mmK-1"
• Use superscripts for powers "10 m3" not "10 m^3". You may use a slash e.g. "9.8 m/s2", but to avoid confusion it is generally better to use negative powers "9.8 m s-2"
• Use × not x for scientific notation, and leave spaces e.g. "3.5 × 105", not "3.5x105"
• Be clear. " 0.142 ± 0.001 " or " (1.42 ± 0.01) × 10-1 " is far easier to read then " 1.42 × 10-1 ± 1 × 10-3 "