Imagine we have a power source produce constants power in Watt. If I placed blue LED, then red LED, which color gives more intensity and wht color gives the most?
Red light is produced by lower-energy photons than blue light is; if you use the same amount of energy for both red and blue sources, then the red light source will be brighter since less energy is used per photon. This means more photons can be produced. This is why your battery-drained headlamp emits such a low intensity white light but can emit a normally-bright red light once you switch modes.
The color that would give the most intensity is the largest wavelength of light possible: a wavelength the size of the universe.
Light intensity should be same. However, the no. of photons will be more in case of red LED as the energy of single photon is less.
Here, the assumption is that efficiency of both led is same. which is fairly true in most cases.
but suppose two lights of same intensity is being shined..the no. of photons of lower frequency will be more than that of higher frequency photons.
so photon flux will be more for red than the blue.
let us check it from some experimental back up.A laser beam and a microwave beam can carry the same amount of energy. In this case the laser beam contains a smaller number of photons, but each photon in the laser beam has a higher energy than the photons in the microwave beam.for energy transfer the amplitude of the wave matters and square of the amplitude determines the intensity.
Removed first part of quote as it was creating some confusion. Though the statement that photon flux and energy flux are proportional was correct and did not mean equality, it is removed for the sake of clarity.
Your human eye and brain are a calibrated system. Our eye is very sensitive to green, 1 watt of green will be about 100 times brighter than a watt of blue. In other words if you had a 1 watt flashlight at night in the woods a blue one would be useless. You can google or wiki luminosity function.
With the same power output any color gives the same intensity, if intensity is defined as power per surface or angle unit.