Transparent and opaque materials (Item No.: P )

Transcription

1 Teacher's/Lecturer's Sheet Printed: ::47 P Transparent and opaque materials (Item No.: P063300) Curricular Relevance Area of Expertise: Physik Education Level: Klasse 7-0 Topic: Optik Subtopic: Lichtausbreitung Experiment: Durchsichtige und undurchsichtige Stoffe Difficulty Preparation Time Execution Time Recommended Group Size Easy 0 Minutes 0 Minutes 2 Students Additional Requirements: Experiment Variations: Different bodies (e.g. plastic triangle, eraser, etc.) Various types of paper or foil (e.g. tracing paper, black paper, transparency foil - size 0 cm b 0 cm) Tracing paper (DIN A4) White paper (DIN A4) Scissors Keywords: Task and equipment Information for teachers Additional Information The transparency of various objects should be investigated in the first ebperiment; then their assignment into three classes is undertaken: i.e. transparent, translucent and opaque. In a second ebperiment the transparency of translucent materials as a function of their thickness is investigated. Both ebperiments can be performed separately. In the supplementary problem the investigation of air in terms of its transparency allows an ebtension of the knowledge that was gained to gaseous substances in the first part of this ebperiment so that the students can appropriately assign further objects and materials from their surroundings to the correct class. Suggestion In order to subjectively evaluate the transparency of different materials, in this ebperiment the students peer into the light source. Because of this it is crucial that the given voltage of 4 V for the light bob is not ebceeded. Remarks In the material list various bodies and different types of paper which the students have or which can be easily obtained are used. Poster paper (black or white), clear film and lens-cleaning paper can be obtained from PHYWE. If these types of paper as well as the items listed in the material list from our supplementary accessories for colour mibing are not available, other suitable items should be chosen; the success of the ebperiment will not be influenced by this. If a diaphragm (from ) from the colour mibing accessories is available, the size of the light bob opening can be reduced and the applied voltage be increased to 6 V DC. Robert-Bosch-Breite 0 Tel: info@phywe.de D Göttingen Fab:

2 Printed: ::47 P Transparent and opaque materials (Item No.: P063300) Task and equipment Task Does light pass through all materials?. To investigate the transparency of different solid materials to light. 2. To investigate what the transparency of transparent (tracing) paper depends on. Robert-Bosch-Breite 0 Tel: info@phywe.de D Göttingen Fab:

3 Printed: ::47 P Equipment Position No. Material Order No. Quantity Light bob, halogen 2V/20 W Block, trapezoidal PHYWE power supply DC: V, 2 A / AC: 6 V, 2 V, 5 A Additional material: Scissors White paper (DIN A4) Tracing paper (DIN A4) Various types of paper or foil (e.g. tracing paper, black paper, transparency foil - size 0 cm b 0 cm) Different bodies (e.g. plastic triangle, eraser, etc.) Robert-Bosch-Breite 0 Tel: info@phywe.de D Göttingen Fab:

4 Printed: ::47 P Set-up and procedure Set-up Place the light bob with its lamp side on a sheet of paper which lies close to the edge of the table. Put the block on the paper. Lay out the other bodies. Fig. Procedure. Dependency of transparency on the type of the solid material Attach the light bob to the power supply's DC-outlet. Set the voltage to 4 V. Fig. 2 Hold the trapezoidal block about 5 cm away from the opening of the light bob. Look through the body at the light source (filament). Robert-Bosch-Breite 0 Tel: info@phywe.de D Göttingen Fab:

5 Printed: ::47 P Fig. 3 Record your observations in the table in the report. Repeat the ebperiment, holding the block upright this time so that the light passes through the roughened surface. Fig. 4 Record your observations in the table in the report. Repeat the ebperiment for all the prepared bodies and paper types. Complete the table with the bodies and paper types you have used and add the corresponding observations. 2. Dependency of an object's transparency on the thickness of the layer Cut the sheet of tracing paper into about 8 equal-sized pieces. Sketch a small figure on one of the pieces. Fig. 5 Robert-Bosch-Breite 0 Tel: info@phywe.de D Göttingen Fab:

6 Printed: ::47 P First, hold the piece with the figure directly in front of the light bob. Fig. 6 Then successively hold 2,3,4,..,8 pieces in front of it. In each case observe the transparency and the visibility of the figure. Note your observations. Supplementary problem Now, plug the light bob into the 2 V AC outlet. Fig. 7 Shake out a blackboard cleaning cloth about 20 cm in front of the light bob. Observe the light path and visibility of the light. Fig. 8 Robert-Bosch-Breite 0 Tel: info@phywe.de D Göttingen Fab:

7 Printed: ::47 P Note your observations. Robert-Bosch-Breite 0 Tel: info@phywe.de D Göttingen Fab:

8 Printed: ::47 P Report: Transparent and opaque materials Result - Table (2 Punkte) Insert your results in the table below. Body Observations Classification of bodies Trapezoidal body (horizontal) Trapezoidal body (on edge) Eraser/Rubber Foil Tracing paper Result - Observation (0 Punkte) Note your observations. Robert-Bosch-Breite 0 Tel: info@phywe.de D Göttingen Fab:

9 Printed: ::47 P Evaluation - Question (0 Punkte) Compare your observations on the transparency of different bodies. Which three classes of transparency can be distinguished? Evaluation - Question 2 (24 Punkte) Use the classification from Question and assign further objects from your surroundings to these groups. transparent bodies translucent bodies opaque bodies Robert-Bosch-Breite 0 Tel: info@phywe.de D Göttingen Fab:

10 Printed: ::47 P Evaluation - Question 3 (0 Punkte) What does the transparency of tracing paper depend on? Formulate a statement. Evaluation - Supplementary problem (0 Punkte) What can you conclude from your observations in the supplementary ebperiment on the transparency of air? What could be the cause of the phenomenon you observed? Robert-Bosch-Breite 0 Tel: info@phywe.de D Göttingen Fab: