In Rutherford's `alpha` particle cexperiment with thin gold faill, 8100 scattered `alpha`-particles per unit ara per unit area per minute were observed at an anle of `60^(@)` . Find the number of scattered `alpha`particles pr unit area per minut e at and angle of `120^(@)`

Explanation

It is give then `theta_(1)=60^(@),theta_(2)=120^(@),N_(1)=8100,N_(2)=?`
Number of `alpha` particle scattered at and angle `theta`,
`Nprop(1)/(sin^(4)((theta)/(2)))rArr(N_(1))/(N_(2))=((sin^(4).theta_(2)/(2)))/((sin^(4)"(theta_(1))/(2)))`
`rArr (8100)/(N_(2)) = ((sin^(4)"(120^(@))/(2)))/((sin^(4)'60^(@)/(2))) rArr (8100)/(N_(2)) = (sin^(4)60^(@))/(sin^(4)30^(@))`
`rArrN_(2)=(8100xx(1)/(16))/((9)/(16))=900`