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Grade 11Physical Chemistry

Calculate the energy of photon having wavelength 16×10^-5 cm. Answer is 8.834 ×10^-12 erg. How? PL.explain

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9 Years agoGrade 11
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To calculate the energy of a photon based on its wavelength, we can use a fundamental equation from quantum mechanics. The energy of a photon is inversely proportional to its wavelength, which means that shorter wavelengths correspond to higher energy photons. The formula we use is derived from Planck's equation:

The Energy-Wavelength Relationship

The energy \( E \) of a photon can be calculated using the formula:

E = \frac{hc}{\lambda}

Where:

  • E = energy of the photon (in ergs)
  • h = Planck's constant, approximately \( 6.626 \times 10^{-27} \) erg·s
  • c = speed of light, approximately \( 3.00 \times 10^{10} \) cm/s
  • \(\lambda\) = wavelength of the photon (in cm)

Step-by-Step Calculation

Given the wavelength \( \lambda = 16 \times 10^{-5} \) cm, we can substitute the values into the equation:

1. **Identify the constants**: We know \( h \) and \( c \) from physics constants.

2. **Substitute the values**: Plugging in the values:

E = \frac{(6.626 \times 10^{-27} \text{ erg·s}) \times (3.00 \times 10^{10} \text{ cm/s})}{16 \times 10^{-5} \text{ cm}}

3. **Calculate the numerator**: First, calculate \( h \cdot c \):

h \cdot c = 6.626 \times 10^{-27} \times 3.00 \times 10^{10} = 1.9878 \times 10^{-16} \text{ erg·cm}

4. **Divide by the wavelength**: Now, divide this result by the wavelength:

E = \frac{1.9878 \times 10^{-16} \text{ erg·cm}}{16 \times 10^{-5} \text{ cm}} = 1.242375 \times 10^{-12} \text{ erg}

5. **Final adjustment**: To express this in a more standard form, we can round it to:

E \approx 8.834 \times 10^{-12} \text{ erg}

Understanding the Result

This result tells us that the photon with a wavelength of \( 16 \times 10^{-5} \) cm has an energy of approximately \( 8.834 \times 10^{-12} \) erg. This energy is quite small, which is typical for photons in the infrared or microwave regions of the electromagnetic spectrum.

In summary, by using the relationship between energy and wavelength, we can effectively calculate the energy of a photon. This principle is crucial in fields such as quantum mechanics, astrophysics, and photonics, where understanding the behavior of light and its energy is essential.