12. Structure
Passive Voice
In passive sentences, the subject of the verb is
not the person or thing (the “agent”) doing the
action.
Structure
Subject + auxiliary verb (be) + main verb (past participle) + (by) +…
13. Structure
Use of the Passive Voice
We use the passive when:
We want to make the active object
more important.
We do not know the active subject.
14. Structure
Look at these examples:
auxiliary verb
subject (be)
1. Atmospheric pressure is closely approximated
by the hydrostatic pressure.
main verb (past
participle)
15. Structure
Look at these examples:
auxiliary verb
subject (be)
2. Standard Atmospheric Pressure is used as a
reference for gas densities and volumes.
main verb (past
participle)
16. Structure
Look at these examples:
subject auxiliary verb
(be)
3. The Standard Atmospheric Pressure is defined
at sea-level.
main verb (past
participle)
17. Structure
Look at these examples:
subject
4. Any instrument that measures air pressure is
called a barometer.
auxiliary verb
(be)
main verb (past
participle)
18. Text 3
Atmospheric pressure
Atmospheric pressure is the force per unit
area exerted into a surface by the weight of air
above that surface in the atmosphere of Earth.
In most circumstances atmospheric pressure is
closely approximated by the hydrostatic
pressure caused by the weight of air above the
measurement point. Low-pressure areas have
less atmospheric mass above their location,
whereas high-pressure areas have more
atmospheric mass above their location.
Likewise, as elevation increases, there is less
overlying atmospheric mass, so that pressure
decreases with increasing elevation.
19. Standard Atmospheric Pressure
Standard Atmospheric Pressure (atm) is used as
a reference for gas densities and volumes. The
Standard Atmospheric Pressure is defined at
sea-level at 273oK (0oC) and is 1.01325 bar or
101325 Pa (absolute). The temperature of 293oK
(20oC) is also used.
20. Measuring Atmospheric
Pressure
Any instrument that measures air pressure is called
a barometer. The first measurement of atmospheric
pressure began with a simple experiment performed
by Evangelista Torricelli in 1643. In his experiment,
Torricelli immersed a tube, sealed at one end, into a
container of mercury. Atmospheric pressure then
forced the mercury up into the tube to a level that
was considerably higher than the mercury in the
container. Torricelli noticed that height of the
mercury varied with changes in outside weather
conditions. The most common type of barometer
used in homes is the aneroid barometer
21. Figure 1: Diagram showing the construction of
Torricelli's barometer.
24. Speaking
Experiment Role-play
Situation: You are in the science experiment contest.
You have to present your project, remember to give
the following science process
1. Observation
2. Hypothesis Forming
3. Data Gathering
4. Performing Experiement to test you hypothesis
5. Results Recording
The rest of other groups are the committee and try to
find out the faults by using some questions.
Make a group of 5
I will give you 10 minutes
25. Writing
Create your own experiment about
“Atmospheric Pressure” by using the following
materials:
Paper
Glass
Water
Then write on the paper and present in front of
class.
