📚 Topic Summary
The Interference Lab Activity for measuring the wavelength of light demonstrates the wave nature of light. When light passes through narrow slits, it diffracts, creating overlapping wave patterns. These patterns result in constructive interference (bright fringes) where waves align and destructive interference (dark fringes) where waves cancel out. By measuring the distance between these fringes and using the geometry of the setup, we can calculate the wavelength of light. This experiment provides direct evidence that light behaves as a wave.
⚛️ Part A: Vocabulary
Match the terms with their definitions:
| Term |
Definition |
| 1. Wavelength |
A. The distance between two consecutive crests or troughs of a wave. |
| 2. Interference |
B. The superposition of two or more waves resulting in a new wave pattern. |
| 3. Diffraction |
C. The bending of waves around obstacles or through narrow openings. |
| 4. Constructive Interference |
D. Interference that results in an increased amplitude. |
| 5. Destructive Interference |
E. Interference that results in a decreased amplitude. |
Answer Key: 1-A, 2-B, 3-C, 4-D, 5-E
📝 Part B: Fill in the Blanks
Complete the following paragraph:
In the interference experiment, light waves pass through two narrow ____(1)____. These waves then ____(2)____, creating an interference pattern on a screen. The bright fringes are a result of ____(3)____ interference, while the dark fringes are a result of ____(4)____ interference. By measuring the distance between the fringes and knowing the distance to the screen, the ____(5)____ of the light can be calculated using the formula $ \lambda = \frac{d \cdot y}{L} $, where $\lambda$ is the wavelength, $d$ is the slit separation, $y$ is the fringe spacing and $L$ is the distance to the screen.
Answer Key: (1) slits, (2) diffract, (3) constructive, (4) destructive, (5) wavelength
🤔 Part C: Critical Thinking
Explain how increasing the distance between the slits in a double-slit experiment affects the interference pattern observed on the screen. How would the spacing between the bright fringes change, and why?