Threshhold frequency is defined as the minimum light frequency necessary to start photo-electric emission from the surface. This frequency is just effecient enough to emit electrons without any additional force or energy. this minimum frequency creates the necessary result that is sought by the person. The photo electric emission for certain metals can occir with threshhold frequency. The importance of this threshhold frequency lies in the fact that this has been used to create numerous instruments like amplifiers for use of people.
I searched for you and i think its Velocity. it would be nice if u put the answer choices though
I'm not from that school but I can help you.
Distance= Time×Speed
= 1800×1.5
= 2700 m
I am not sure it's right. the question itself is confusing.
Answer:
Explanation:
The work function of the metal corresponds to the minimum energy needed to extract a photoelectron from the metal. In this case, it is:
So, the energy of the incoming photon hitting on the metal must be at least equal to this value.
The energy of a photon is given by
where
h is the Planck's constant
c is the speed of light
is the wavelength of the photon
Using 
and solving for , we find the maximum wavelength of the radiation that will eject electrons from the metal:
And since
1 angstrom = 
The wavelength in angstroms is
