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A student studying the photoelectric effect from twodifferent metals records the

ID: 1727256 • Letter: A

Question

A student studying the photoelectric effect from twodifferent metals records the following information: (i) thestopping potential for photoelectrons released from metal 1 is 1.48V larger than that for metal 2, and (ii) the threshold frequencyfor metal 1 is 40.0% smaller than that for metal 2. Determine thework function for each metal. What would be the final answer? Details: Given       stopping potential for metal-1   = 1.48 V        stopping potentialfor metal - 2 = V         Thresholdfreqency for metal -1 = - 0.4 = 0.6          Thresholdfrequency of metal -2   =             There fore the relation between   stoppingpotential , threshold frequency and work function                                      eV = h f -                              substitute the values inthe above equation                      so    ,                                     For metal - 1                         e ( V + 1.48 ) = h c / 0.6     -1   The work function of metal -1                        1   = hc / 0.6 - e (V+1.48 )                          For metal - 2                         e V =   h c / - 2   The work function of metal -2                          2 = h c / - eV          where       h = plancksconstant                              = 6.63 x 10-34 Js                          c  = speed of light                              = 3 x 108       m/s                          e = charge of electron                              = 1.6 x 10-19 C A student studying the photoelectric effect from twodifferent metals records the following information: (i) thestopping potential for photoelectrons released from metal 1 is 1.48V larger than that for metal 2, and (ii) the threshold frequencyfor metal 1 is 40.0% smaller than that for metal 2. Determine thework function for each metal. What would be the final answer? Details: Given       stopping potential for metal-1   = 1.48 V        stopping potentialfor metal - 2 = V         Thresholdfreqency for metal -1 = - 0.4 = 0.6          Thresholdfrequency of metal -2   =             There fore the relation between   stoppingpotential , threshold frequency and work function                                      eV = h f -                              substitute the values inthe above equation                      so    ,                                     For metal - 1                         e ( V + 1.48 ) = h c / 0.6     -1   The work function of metal -1                        1   = hc / 0.6 - e (V+1.48 )                          For metal - 2                         e V =   h c / - 2   The work function of metal -2                          2 = h c / - eV          where       h = plancksconstant                              = 6.63 x 10-34 Js                          c  = speed of light                              = 3 x 108       m/s                          e = charge of electron                              = 1.6 x 10-19 C Given       stopping potential for metal-1   = 1.48 V        stopping potentialfor metal - 2 = V         Thresholdfreqency for metal -1 = - 0.4 = 0.6          Thresholdfrequency of metal -2   =             There fore the relation between   stoppingpotential , threshold frequency and work function                                      eV = h f -                              substitute the values inthe above equation                      so    ,                                     For metal - 1                         e ( V + 1.48 ) = h c / 0.6     -1   The work function of metal -1                        1   = hc / 0.6 - e (V+1.48 )                          For metal - 2                         e V =   h c / - 2   The work function of metal -2                          2 = h c / - eV          where       h = plancksconstant                              = 6.63 x 10-34 Js                          c  = speed of light                              = 3 x 108       m/s                          e = charge of electron                              = 1.6 x 10-19 C

Explanation / Answer

hf - W1 = e1 hf - W2 = e21 -2 = 1.48 V 1.48 eV = W2 - W1 hfs1 = W1 hfs2 = W2fs1 =0.6fs2 W1 = 0.6W2 1.48 eV = 0.4W2 W2 = 3.7 eV W1 = 2.22 eV