PHYS 1407 – Conceptual Physics II

Light Sources

Leader: ___________________ Recorder: __________________________

Skeptic: ___________________ Encourager: ________________________

Materials

For Each Table

Hand-held Spectrometer

Flashlight

Set-up In the Room

Known Incandescent Source

Known Luminescent Sources

Known Emission Sources

Unknown Sources

Introduction

In this activity we will learn to describe different sources of light by features of their spectra. The light sources we will characterize include incandescent, emission, and luminescent sources.

Procedure

1. View the known incandescent source with your eye.

Q1. Describe the appearance of the light from the incandescent source.

Q2. Describe any other relevant features of the incandescent source.

2. View the incandescent source through the spectrometer.

Q3. Describe the appearance of the incandescent source’s spectra as seen through the spectrometer.

3. View the four known luminescent sources with your eye.

Q4. Describe the appearance of the light from the luminescent sources.

Q5. Describe any other relevant features of the luminescent sources.

4. View the four known luminescent sources through the spectrometer. Note that you will probably have to hold the sources next to slit of the spectrometer to see the spectrum.

Q7. Describe the appearance of the four known luminescent sources’ spectra as seen through the spectrometer.

Q8. In what ways does the light from the luminescent source differ from the light from the incandescent source?

Q9. In what ways is the light from the luminescent sources similar to the light from the incandescent source?

5. View the known emission sources with your eye.

Q10. Describe the appearance of the light from the emission sources.

Q11. Describe any other relevant features of the emission sources.

6. View the known emission sources through the spectrometer.

Q12. Describe the appearance of the emission sources’ spectra as seen through the spectrometer.

Q13. In what ways does the light from the emission sources differ from the light from the incandescent source?

Q14. In what ways is the light from the emission sources similar to the light from the incandescent source?

Q15. In what ways does the light from the luminescent sources differ from the light from the emission sources?

Q16. In what ways is the light from the luminescent sources similar to the light from the emission sources?

7. View the light from the flashlight with your eye

P17. Based on your observation predict is the flashlight an incandescent, luminescent, or emission source?

8. View the light from the flashlight through the spectrometer.

Q18. Does the spectrum of the light from the flashlight agree with your prediction? Explain.

9. View the obnoxious orange light from the near the instructor’s desk with your eye.

P19. Based on your observation predict is the obnoxious orange light an incandescent, luminescent, or emission source?

10. View the light from the obnoxious orange light through the spectrometer.

Q20. Does the spectrum of the light from the obnoxious orange light agree with your prediction? Explain.

11. View through the window the light emitted light from the rocks in the cardboard box.

P21. Based on your observation predict are the rocks in the cardboard box an incandescent, luminescent, or emission source?

12. View the light from the rocks in the cardboard box through the spectrometer.

Q22. Does the spectrum of the light from the rocks in the cardboard box agree with your prediction? Explain.

S23. Could you always predict correctly if a light source was incandescent, luminescent or emission?

S24. How can viewing the spectrum of a light source clarify the type of light source it is?