Monochromatic radiation emitted when electronon hydrogen atom jumps fr...
To find the threshold frequency of the material, we need to use the formula for the stopping potential in the photoelectric effect:
V_stop = (h/λ) - (φ/e)
Where:
V_stop is the stopping potential (3.57 V in this case)
h is Planck's constant (6.626 x 10^-34 J*s)
λ is the wavelength of the monochromatic radiation emitted (which corresponds to the transition from the first excited state to the ground state of hydrogen)
φ is the work function of the material (which represents the minimum energy required to remove an electron from an atom in the material)
e is the elementary charge (1.602 x 10^-19 C)
Since we are given the wavelength, we can convert it to frequency using the equation:
c = λ * ν
Where:
c is the speed of light (3 x 10^8 m/s)
ν is the frequency
Solving for ν, we get:
ν = c / λ
Now we can substitute this expression for ν into the formula for the stopping potential:
V_stop = (h / (c / λ)) - (φ / e)
Simplifying, we get:
V_stop = (hc / λ) - (φ / e)
Since we are looking for the threshold frequency, we want the stopping potential to be zero. Therefore, we can set V_stop = 0 and solve for the threshold frequency:
0 = (hc / λ) - (φ / e)
Solving for λ, we get:
λ = (hc / (φ / e))
Now we can plug in the given values:
h = 6.626 x 10^-34 J*s
c = 3 x 10^8 m/s
φ = unknown (to be determined)
e = 1.602 x 10^-19 C
Plugging in these values, we get:
λ = (6.626 x 10^-34 J*s * 3 x 10^8 m/s) / ((φ / (1.602 x 10^-19 C))
Simplifying, we get:
λ = (19.878 x 10^-26 J*m) / (φ / 1.602 x 10^-19 C)
Now we can rearrange the equation to solve for φ:
φ = (19.878 x 10^-26 J*m) / (λ / 1.602 x 10^-19 C)
Substituting the given stopping potential of 3.57 V, we get:
φ = (19.878 x 10^-26 J*m) / (3.57 V / 1.602 x 10^-19 C)
Simplifying, we get:
φ = (19.878 x 10^-26 J*m * 1.602 x 10^-19 C) / (3.57 V)
φ = 8.913 x 10^-7 J
Now we can substitute this value for φ back into the equation for λ:
λ = (6.626 x 10^-34 J*s * 3 x 10^8 m/s) / ((8.913 x 10^-7 J) / (1.602 x 10^-19 C))
Simplifying, we get:
λ = (19.878 x 10^-26 J*m) / (8.913 x 10^-7