Young's Double Slit Experiment
Simulate the historic Young's experiment. By adjusting the distance between slits ($d$) and the screen distance ($D$), measure the **fringe width ($\beta$)** to calculate the **wavelength ($\lambda$)** of the monochromatic light source.
Help & Instructions
▼- **Adjust Parameters:** Use the sliders to set the Slit Separation ($d$) and Screen Distance ($D$).
- **Observe $\mathbf{\beta}$:** The simulation calculates the **Fringe Width ($\beta$)** based on the formula.
- **Adjust $\mathbf{\lambda}$:** Change the source Wavelength ($\lambda$) to observe its effect on the pattern.
- **Analyze Stats:** Note how $\beta$ changes with $d$, $D$, and $\lambda$.
- **Calculate $\mathbf{\lambda}$:** Use the $\beta$, $D$, and $d$ values to calculate the wavelength.
- Understand the phenomenon of **interference** and **coherence**.
- Relate the Fringe Width ($\beta$) to $\lambda, D,$ and $d$.
- Calculate the wavelength of light using the formula $\lambda = \frac{\beta d}{D}$.
Experiment Setup and Results
Formula used: $\beta = \frac{\lambda D}{d}$
Fringe Width Calculation:
Fringe Width: $\beta = \frac{\lambda D}{d}$
$\beta = \frac{(600 \times 10^{-9} \text{ m}) \times 1.0 \text{ m}}{(0.50 \times 10^{-3} \text{ m})} = 0.00120 \text{ m} = 1.20 \text{ mm}$
Young's experiment proved the wave nature of light. When light passes through two closely spaced, **coherent** sources (slits), the waves interfere, creating alternating bright (constructive) and dark (destructive) **fringes** on a screen.
Detailed Physics Explanation
The fringe width is the distance between two consecutive bright or dark fringes. It is directly proportional to the **wavelength ($\lambda$)** and the **screen distance ($D$)**, and inversely proportional to the **slit separation ($d$)**.
- **Bright Fringes (Maximas):** Occur when path difference $\Delta x = n\lambda$ ($n=0, 1, 2, ...$)
- **Dark Fringes (Minimas):** Occur when path difference $\Delta x = (n + \frac{1}{2})\lambda$ ($n=0, 1, 2, ...$)
For a stable interference pattern to be observed, the two light sources must be **coherent**—meaning they must maintain a constant phase difference and have the same frequency (wavelength). The single slit preceding the double slit ensures this coherence.
