Question

If K₁ and K_­2 are the maximum kinetic energies of photo electrons emitted when lights of wavelength λ₁ and λ₂ respectively incident on a metallic surface and λ₁ = 3λ₂ . Then

• A. K₁>
• B. K₁<
• C. K₁ = 3K₂
• D. K₂ = 3K₁

Answer 1

Answer: (B)

K₁<

Answer 2

K₁ = $\frac { \mathrm { hc } } { \lambda _ { 1 } }$ – φ

K₂ = – φ

= $\frac { \left( \frac { 3 h c } { \lambda _ { 1 } } - \phi \right) } { \left( \frac { \mathrm { hc } } { \lambda _ { 1 } } - \phi \right) }$ = $\frac { 3 \left( \frac { \mathrm { hc } } { \lambda _ { 1 } } - \frac { \phi } { 3 } \right) } { \left( \frac { \mathrm { hc } } { \lambda _ { 1 } } - \phi \right) }$

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