1.

Lights of two different frequencies whose photons have energies 1 and 2.5 eV, respectively, successively illuminate a metal whose work function is 0.5 eV. The ratio of the maximum speeds of the emitted electronsA. `1:5`B. `1:4`C. `1:2`D. `1:1`

Answer» Correct Answer - C
If E is the energy of incident photon and W the work function, then `E_W_0="available energy"`
`E-W_0=(1)/(2)mv^(2)`
or `v=sqrt((2(E-W_0))/(m))`
`(v_1)/(v_2)=sqrt((1-0.5)/(2.5-0.5))=sqrt((0.5)/(2))=(1)/(2)`


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