How many photons are contained in a flash of green light (525 nm) that contains 189 kj of energy?

There are 4.99 × 10²³  photons contained in a flash of green light (525 nm) that contains 189 kJ of energy.

First, we will calculate the energy (E) of each photon using the Planck-Einstein's relation.

where,

Each photon has an energy of 3.79 × 10⁻¹⁹ J. The number of photons that amount to 189 kJ (189 × 10³ J) of energy are:

There are 4.99 × 10²³  photons contained in a flash of green light (525 nm) that contains 189 kJ of energy.

You can learn more about photons here:

they begin to vibrate harder causing the material that was solid to turn into a liquid i.e gallium or ice