Physical quantities and units

SI units

SI units defines 7 base quantities and units.
QUANTITIES                                UNITS
Time-> t                                second-> s
Length-> l                              metre-> m
Mass-> m                              kilogram-> kg
Temperature-> T                    kelvin-> K
Electric current-> I                 ampere-> A
Amount of substance-> n        mole-> mol
Luminous intensity                   candela-> cd

We use prefixes for SI units such as tera, giga, mega, kilo, deci etc. They all are representations of the standard forms.

Basic Laboratory Orientation

What should you do when in the laboratory.

1) When you accidentally spill some strong acid onto your skin, you should wash it thoroughly with plenty of water.

2) If there is excess acid from your experiment, you should pour the acid into a special bottle meant for disposal and follow instructions from the teacher.

3) A non-luminous flame should not be left alone as it cannot be seen easily and other people might not see the flame and burn themselves.

4) The best way to light a Bunsen burner is to open the air-hole ignite a lighter near the mouth of the barrel and turn on the gas tap slowly.

5) Adult supervision is required for students to enter the science laboratory as the laboratory can be a dangerous place if the users are not careful.

6) You should not run around in the laboratory as the laboratory is very dangerous as they might be injured.
7) If there is anything broken in the laboratory, the teacher must be informed immediately as others may get hurt.

Graphs

Graphing Scientific Data

Sometimes, we plot scientific data that is recorded in a graph format. The graph is made up of the x and y-axis and at the top of the graph, it is usually the y-axis against the x-axis. We have to scale the graph so that it covers about 3/4 of the page. Scales should not differ by multiples of 3 as well. Each of the graph points has to be marked by an X. We don't connect all of the points but we either draw a best fit line or a best fit curve. We draw the best fit line by drawing the line in the average of the points. If one of the scales has 1 d.p., the rest of the scales must also have 1 d.p.

Variables

Different types of variables

I learnt about the different types of variables. They are the independent variable, dependent variable and controlled variable.
1) The independent variable is the one whose values is the one chosen by the experimenter. In other words, it is the variable that is modified.
2) The dependent variable is the value you observe and record in an experiment and it depends on the behaviour of the participant.
3) The constant variable is the factors that scientists keeps constant.