practical skills Flashcards
Protractor
Smallest division, 1 degree
Ruler
Smallest division, 0.1cm
Electronic balance
Smallest division, 0.1g
Spring balance
Smallest division, 0.1N
Measuring cylinder
Half smallest division, 0.5 cm cube
Thermometer
Half smallest division, 0.5 degree Celsius
Ammeter
Half smallest division, 0.01A
Milliammeter
Half smallest division, 1 mA
Voltmeter
Half smallest division, 0.05 V
Stopwatch
Due to reaction time, 0.1s
Significant figures/decimal places for calculated quantities - addition/subtraction
Least number of decimal places
Significant figures/decimal places for calculated quantities - multiplication / division
Least number of significant figures
Significant figures/decimal places for calculated quantities - exceptions
1: calculating data value T, the significant figures of n is not taken into account as it has no inherent error
2: when trigonometry operators are used, the answer should have the same number of significant figures as the raw data
Recording readings - raw data & processed data
Raw data on the left hand side, processed data on the right hand side
Recording readings- headings
Conventional symbols with appropriate units included
Recording readings - record of values
Don’t write the units inside the table , do not show any calculations within the table
Recording readings- first column
- Independent variable
- arranged in increasing or decreasing order
- same number of decimal places
- Regular increments
- difference of largest and smallest reading should be over half of what is available to be changed
Recording readings - second column
- Dependent variable
- measurements of dependent variable are repeated to obtain an average
Graph plotting - axes
- Axes must be thin and drawn on the printed and lines
- both axes must be labelled
- regular intervals, no fractions
Graph plotting - scale
Ratios: 1:1, 1:2,1:5
Graph plotting-points
Use a small cross to mark your points clearly, points must be plotted to half the smallest division
Graph plotting-line
Best fit line minimizes the distance between the points and the line.
avoid anomalous points.
Graph plotting-gradient
- Label the gradient coordinates in the graph clearly, to half the smallest division.
- y1-y2 / x1-x2
Graph plotting -graphical analysis
- Line is straight and passes through origin: y is directly proportional to x
- line is straight but does not pass through origin: y increases linearly with x
- line is straight but does not pass through origin (downwards): y decreases linearly x
- if the curve has a general positive gradient: as x increases, y increases non-linearly
