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Multiple Choice
A carbon dioxide laser produces electromagnetic waves, which pass through a circular aperture with diameter . What is the approximate width of the laser beam when it strikes a target away?
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Verified step by step guidance
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Understand that the problem involves diffraction of light through a circular aperture, which can be analyzed using the formula for the angular width of the central maximum in a diffraction pattern: \( \theta = 1.22 \frac{\lambda}{D} \), where \( \lambda \) is the wavelength and \( D \) is the diameter of the aperture.
Substitute the given values into the formula: \( \lambda = 10.6 \times 10^{-6} \) m and \( D = 1.0 \times 10^{-3} \) m. Calculate \( \theta \) using \( \theta = 1.22 \frac{10.6 \times 10^{-6}}{1.0 \times 10^{-3}} \).
Once \( \theta \) is calculated, use the small angle approximation to find the width of the laser beam at the target distance. The width \( W \) can be approximated by \( W = L \cdot \theta \), where \( L \) is the distance to the target (3.0 m).
Substitute \( L = 3.0 \) m and the calculated \( \theta \) into the formula \( W = 3.0 \cdot \theta \) to find the width of the laser beam.
Compare the calculated width \( W \) with the given options (12 cm, 15 cm, 19 cm, 22 cm, 26 cm) to determine which is closest to the calculated value.