For alkali metals threshold frequencies lie in which region?

For most metals threshold frequencies lie in which region?

For most of metals threshold frequency lies in which region of electro-magnetic radiation?

Define threshold frequency.

Value of threshold frequency depend on which factors?

For given metal plate threshold frequency is V_(0) . When radiation of 2V_(0) is incident on metal surface ,maximum velocity of photoelectron emitted is V_(1) when frequency of incident radiation is charged to 5V_(0) ,maximum velocity of photoelectron emitted is v_(2) .Ration of v_(1) and v_(2) is .....

If ratio of threshold frequencies of two metals is 1:3 ,ratio of their work function is ……