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CGP EDU Academic Team
Published on: September 12, 2026
A source emitting two light waves of wavelengths 580 nm and 700 nm is used in a young's double slit interference experiment. The separation between the slits is 0.20 mm and the interference is observed on a screen placed at 150 cm from the slits. Find the linear separation between the first maximum (next to the central maximum) corresponding to the two wavelengths.
Text Solution
Verified by ExpertsThe correct answer is:
B
Step 1: Determine the paths of each wavelength to find the position of the first maximum. The position of the maxima in a double slit interference pattern is given by:
$$ y = \frac{m \lambda L}{d} $$
where:
Step 2: Calculate for the wavelength $\lambda_1 = 580 \text{ nm} = 580 \times 10^{-9} \text{ m}$:
$$ y_1 = \frac{1 \times (580 \times 10^{-9}) \times 1.5}{0.0002} $$
$$ y_1 = \frac{8.7 \times 10^{-7}}{0.0002} = 0.00435 \text{ m} = 4.35 \text{ mm} $$
Step 3: Calculate for the wavelength $\lambda_2 = 700 \text{ nm} = 700 \times 10^{-9} \text{ m}$:
$$ y_2 = \frac{1 \times (700 \times 10^{-9}) \times 1.5}{0.0002} $$
$$ y_2 = \frac{1.05 \times 10^{-6}}{0.0002} = 0.00525 \text{ m} = 5.25 \text{ mm} $$
Step 4: Calculate the linear separation between the first maxima for the two wavelengths:
$$ \Delta y = y_2 - y_1 = 5.25 \text{ mm} - 4.35 \text{ mm} = 0.90 \text{ mm} $$
Step 5: Therefore, the linear separation between the first maximum (next to the central maximum) corresponding to the wavelengths 580 nm and 700 nm is 0.90 mm.
$$ y = \frac{m \lambda L}{d} $$
where:
- $y$ = distance from the central maximum to the m-th maximum
- $m$ = order of the maximum (1 for the first maximum)
- $\lambda$ = wavelength of the light
- $L$ = distance from the slits to the screen (150 cm = 1.5 m)
- $d$ = separation between the slits (0.20 mm = 0.0002 m)
Step 2: Calculate for the wavelength $\lambda_1 = 580 \text{ nm} = 580 \times 10^{-9} \text{ m}$:
$$ y_1 = \frac{1 \times (580 \times 10^{-9}) \times 1.5}{0.0002} $$
$$ y_1 = \frac{8.7 \times 10^{-7}}{0.0002} = 0.00435 \text{ m} = 4.35 \text{ mm} $$
Step 3: Calculate for the wavelength $\lambda_2 = 700 \text{ nm} = 700 \times 10^{-9} \text{ m}$:
$$ y_2 = \frac{1 \times (700 \times 10^{-9}) \times 1.5}{0.0002} $$
$$ y_2 = \frac{1.05 \times 10^{-6}}{0.0002} = 0.00525 \text{ m} = 5.25 \text{ mm} $$
Step 4: Calculate the linear separation between the first maxima for the two wavelengths:
$$ \Delta y = y_2 - y_1 = 5.25 \text{ mm} - 4.35 \text{ mm} = 0.90 \text{ mm} $$
Step 5: Therefore, the linear separation between the first maximum (next to the central maximum) corresponding to the wavelengths 580 nm and 700 nm is 0.90 mm.
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