Transparency Master |
This simple detector will allow you to measure changes in the cosmic ray intensity at the Earth's surface. It works on a very simple principle. Cosmic rays cause ordinary air to become conductive through the process of ionization. Each ionized path acts as an electrical conductor for electrons stored on the aluminum foil "leaves" of the detector sealed inside a glass jar. |
Transparency Master |
The materials required can be any readily available glass jar (with lid), a cork
through which a small hole has been drilled, some stiff aluminum wire and aluminum foil or (Optional: ping-pong ball, and metallic aluminum paint.) Drill or file a hole in the centre of the lid into which you will insert the cork insulator. Assemble the electroscope (as shown below) and then assemble the detector as shown to the left. [DANGER: Inserting the aluminum wire through the hole in the cork could cause serious injury to the hands - use extreme care] |
Transparency Master |
At the core of the cosmic ray detector is an aluminum foil leaf electroscope.
The foil leaves are constructed as shown in the diagram to the left. The leaves are suspended on an aluminum wire which is suspended in a small jam jar (or similar bottle) to protect the delicate leaves from air currents. A cork plug is used to support the aluminum wire and to electrically isolate the wire from the lid of the jar. It is important to have the electroscope assembly electrically isolated. |
Transparency Master |
To detect cosmic rays the detector must first be "charged" with electrons. This is accomplished by touching the aluminum ball with an object which has been given a large negative electrostatic charge. |
Transparency Master |
Using a stopwatch (or watch with a second hand) measure the time required for the electroscope leaves in the detector to fall to a specific level. The greater the intensity of the ionizing radiation in the jar, the greater the cosmic radiation intensity.
The rate of discharge is also sensitive to changes in the water vapour content of the air in the jar, so sealing the jar with wax or tape helps produce more reliable readings. |
ASSESSMENTThe chart that follows identifies four levels of achievement for assessing students' communication of information and ideas. Levels 1 and 2 describe performance that is approaching the standard for the grade; level 3 describes the standard for the grade; and level 4 describes performance that is above the standard. In numerical terms, all four levels are at passing level for the grade. Level 1 corresponds to a mark of 50%-59%; level 2, 60%-69%; level 3, 70%-79%; and level 4, 80%-100% . Student performance that is not approaching or is significantly below the standard would receive a failing grade. |
|||
|
Inquiry
The student: |
|||
|
Level 1
|
Level 2
|
Level 3
|
Level 4
|
| applies the skills and strategies of scientific inquiry, (e.g. performing and recording, analysing and interpreting, and problem solving), in constructing and using an electroscope cosmic ray detector with limited competence | applies the skills and strategies of scientific inquiry, (e.g. performing and recording, analysing and interpreting, and problem solving), in constructing and using an electroscope cosmic ray detector with moderate competence | applies the skills and strategies of scientific inquiry, (e.g. performing and recording, analysing and interpreting, and problem solving), in constructing and using an electroscope cosmic ray detector with considerable competence | applies all of the skills and strategies of scientific inquiry, (e.g. performing and recording, analysing and interpreting, and problem solving), in constructing and using an electroscope cosmic ray detector with a high degree of competence |
| uses tools, equipment, and materials safely and correctly only with supervision | uses tools, equipment, and materials safely and correctly with some supervision | uses tools, equipment, and materials safely and correctly | demonstrates and promotes the safe and correct use of tools, equipment, and materials |
[Home]
Prepared by the YES I Can! Science Team,