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A sodium metal piece is illuminated with...

A sodium metal piece is illuminated with light of wavelength 0.3 `mum`. The work function of sodium is 2.46 eV. For this situation ,mark out the correct statement (s).

A

The maximum kinetic energy of the ejected photoelectrons is 1.68 eV

B

The cut-off wavelength for sodium is 505 nm

C

The minimum photon energy of incident light for photoelectric effect to take place is 2.46 eV

D

All of the above

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The correct Answer is:
To solve the problem, we will follow these steps: ### Step 1: Calculate the Energy of Incident Light We start by calculating the energy of the incident light using the formula: \[ E = \frac{hc}{\lambda} \] Where: - \( h \) (Planck's constant) = \( 6.626 \times 10^{-34} \, \text{J s} \) - \( c \) (speed of light) = \( 3.00 \times 10^{8} \, \text{m/s} \) - \( \lambda \) (wavelength) = \( 0.3 \, \mu m = 0.3 \times 10^{-6} \, m \) Substituting the values: \[ E = \frac{(6.626 \times 10^{-34} \, \text{J s})(3.00 \times 10^{8} \, \text{m/s})}{0.3 \times 10^{-6} \, m} \] Calculating the energy: \[ E = \frac{1.9878 \times 10^{-25}}{0.3 \times 10^{-6}} = 6.626 \times 10^{-19} \, \text{J} \] Now, convert this energy from joules to electron volts (1 eV = \( 1.6 \times 10^{-19} \, \text{J} \)): \[ E = \frac{6.626 \times 10^{-19}}{1.6 \times 10^{-19}} \approx 4.14 \, \text{eV} \] ### Step 2: Calculate the Maximum Kinetic Energy of Ejected Electrons Using Einstein's photoelectric equation: \[ K.E. = E - \phi \] Where \( \phi \) (work function of sodium) = 2.46 eV. Substituting the values: \[ K.E. = 4.14 \, \text{eV} - 2.46 \, \text{eV} = 1.68 \, \text{eV} \] ### Step 3: Calculate the Cutoff Wavelength The cutoff wavelength \( \lambda_0 \) can be calculated using the work function: \[ \phi = \frac{hc}{\lambda_0} \] Rearranging gives: \[ \lambda_0 = \frac{hc}{\phi} \] Substituting the values: \[ \lambda_0 = \frac{(6.626 \times 10^{-34} \, \text{J s})(3.00 \times 10^{8} \, \text{m/s})}{2.46 \times 1.6 \times 10^{-19} \, \text{J}} \] Calculating: \[ \lambda_0 = \frac{1.9878 \times 10^{-25}}{3.936 \times 10^{-19}} \approx 5.05 \times 10^{-7} \, m = 505 \, nm \] ### Step 4: Determine the Minimum Photon Energy The minimum photon energy required for the photoelectric effect to occur is equal to the work function: \[ E_{min} = \phi = 2.46 \, \text{eV} \] ### Conclusion Based on the calculations: 1. The maximum kinetic energy of ejected electrons is \( 1.68 \, \text{eV} \) (Correct). 2. The cutoff wavelength of sodium is \( 505 \, nm \) (Correct). 3. The minimum photon energy for the photoelectric effect is \( 2.46 \, \text{eV} \) (Correct). Thus, all statements are correct.

To solve the problem, we will follow these steps: ### Step 1: Calculate the Energy of Incident Light We start by calculating the energy of the incident light using the formula: \[ E = \frac{hc}{\lambda} \] Where: ...
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