question_answer

A certain metal was irradiated with light of frequency \[3.2\times {{10}^{16}}{{\sec }^{-1}}\]. The photoelectrons emitted have twice the kinetic energy as photoelectrons emitted when the same metal is irradiated with a light of frequency \[2\times {{10}^{16}}{{\sec }^{-1}}\]. The threshold frequency of the metal is \[x\times {{10}^{15}}{{\sec }^{-1}}\]. The value of x is ___.

Answer:

8