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Radiations of monochromatic waves of wavelength 400 nm are incident on the surface of metals Zn, Fe and Ni of work function 3.4 eV,4.2 eV and 4.8 eV respectively, then (take hc=12400 eV−A )

A. Maximum kinetic energy associated with photoelectrons from the surface of any metal is 0.3eV No photoelectrons are emitted from
B. the surface of Fe
C. If the frequency of source of radiations is doubled then kinetic energy of photoelectrons is also doubled
D. Photoelectrons will be emitted from the surface of all the three metals if the wavelength of incident radiations is less than 200 nm

User PhE
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1 Answer

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Final answer:

The correct answer is (B) No photoelectrons are emitted from the surface of Fe. The maximum kinetic energy of photoelectrons from the surface of metals can be calculated using the equation E = hv - φ, where E is the maximum kinetic energy, hv is the energy of the incident photon, and φ is the work function of the metal. Using the given work functions, we find that no photoelectrons are emitted from the surface of iron.

Step-by-step explanation:

The maximum kinetic energy of photoelectrons can be calculated using the equation:

E = hv - φ

Where E is the maximum kinetic energy, hv is the energy of the incident photon, and φ is the work function of the metal.

To find the maximum kinetic energy associated with photoelectrons from the surface of each metal, we can use the given work functions and the equation:

E = (hc/λ) - φ

For zinc (Zn), with a work function of 3.4 eV and incident radiation of wavelength 400 nm:

E = (12400 eV-A *eV-A nm)/(400 nm) - 3.4 eV

= 1.24 eV - 3.4 eV

= -2.16 eV

Since the maximum kinetic energy cannot be negative, no photoelectrons are emitted from the surface of zinc (Option B).

For iron (Fe), with a work function of 4.2 eV and incident radiation of wavelength 400 nm:

E = (12400 eV-A *eV-A nm)/(400 nm) - 4.2 eV

= 1.24 eV - 4.2 eV

= -2.96 eV

Since the maximum kinetic energy cannot be negative, no photoelectrons are emitted from the surface of iron (Option B).

For nickel (Ni), with a work function of 4.8 eV and incident radiation of wavelength 400 nm:

E = (12400 eV-A *eV-A nm)/(400 nm) - 4.8 eV

= 1.24 eV - 4.8 eV

= -3.56 eV

Since the maximum kinetic energy cannot be negative, no photoelectrons are emitted from the surface of nickel (Option B).

User Rougepied
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