Answer: A is your answer i am sorry if i am wrong
Explanation:
he first PLCs were programmed with a technique that was based on relay logic wiring schematics. This eliminated the need to teach the electricians, technicians and engineers how to program a computer - but, this method has stuck and it is the most common technique for programming PLCs today.
Answer:
Explanation:
The energy of a photon is given by the equation , where h is the <em>Planck constant</em> and f the frequency of the photon. Thus, N photons of frequency f will give an energy of .
We also know that frequency and wavelength are related by , so we have , where c is the <em>speed of light</em>.
We will want the number of photons, so we can write
We need to know then how much energy do we have to calculate N. The equation of power is , so for the power we have and considering 1 second we can calculate the total energy, and then only consider the 4% of it which will produce light, or better said, the N photons, which means it will be .
Putting this paragraph in equations:
.
And then we can substitute everything in our equation for number of photons, in S.I. and getting the values of constants from tables: