Answer:
3
Explanation:
the answer is number three
The energy of a single photon is given by:

where
E is the energy
h is the Planck constant
f is the frequency of the light
The light in our problem has a frequency

, so the energy of each photon of that light is:
Answer:
B) Yes, but only those electrons with energy greater than the potential difference established between the grid and the collector will reach the collector.
Explanation:
In the case when the collector would held at a negative voltage i.e. small with regard to grid So yes the accelerated electrons would be reach to the collecting plate as the kinetic energy would be more than the potential energy that because of negative potential
so according to the given situation, the option b is correct
And, the rest of the options are wrong
To solve this problem it is necessary to apply the second derivative of the function to find the maximum time reference and thus calculate the maximum voltage.
With the maximum voltage by Ohm's Law it is possible to find the maximum current.
Ohm's law defines that
E = I*R
Where,
I = Current
R= Resistance
On the other hand by faraday studies and the potential can be expressed at the rate of change of the electric flow, that is

Replacing with our values we have that


The second derivative is

When E' = 0 we have a Maximum, then
0 = -36t+36
t = 1
Therefore when the time is 1s E has a Maximum, replacing at the function



Then the maximum current will be given by



Therefore the maximum current induced in the ring is 6.42A
the answer is 1.5 hope this helps