A student studied the photoelectric effect from two different metals by performing two separate

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15 A student studying the photoelectric effect from two different metals Using

Text Solution

Solution : (i) Here, threshold frequency of A, `v_(0A)=5xx10^(14)Hz` and of B, <br> `v_(0B)=10xx10^(14)Hz`. <br> Work function, `phi_(0)=hv_(o) or phi_(0) prop v_(0)` <br> `:. (phi_(0A))/(phi_(0B))=(5xx10^(14))/(10xx10^(14))lt1 or phi_(0A)lt phi_(0B)` <br> Therefore, work function is higher for material B than A. <br> (ii) For metal A, `slope =h/e=2/((10-5)10^(14)) or h=(2xxe)/(5xx10^(14)) =(2xx1.6xx10^(-19))/(5xx10^(14)) =6.4xx10^(-34)Js` <br> For metal B, `slope =h/e=2/((15-10)10^(14)) or h=(2.5xxe)/(5xx10^(14)) =(2.5xx1.6xx10^(19))/(5xx10^(14)) =8xx10^(-34)Js` <br> Since, the value of h from experiment for metals A and B is different. Hence, experiment is not consistent with theory.

Text Solution

`3.2xx10^(-34)Js,4xx10^(-34)Js``6.4xx10^(-34)Js,8xx10^(-34)Js``1.2xx10^(-34)Js,3.2xx10^(-34)Js``4.2xx10^(-34)Js,5xx10^(-34)Js`

Answer : B

Solution : (b) : <img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/NCERT_OBJ_FING_PHY_XII_C11_E01_022_S01.png" width="80%"> <br> For metal A, Slope `=(h)/(e)=(2-0)/((10-5)xx10^(14))` <br> `or h=(2xxe)/(5xx10^(14))=(2xx1.6xx10^(-19))/(5xx10^(14))=6.4xx10^(-34)J` s <br> For metal B, Slope `=(h)/(e)=(2.5-0)/((15-10)xx10^(14))` <br> ` h=(2.5xxe)/(5xx10^(14))=(2.5xx1.6xx10^(-19))/(5xx10^(14))=8xx10^(-34)J` s