Amount of light

The quantity of light delivered by radiation whose flux is \(\phi\) for a duration \(\Delta t=t_{2}-t_{1}\) is given by

f = ∫ t 1 t 2 Φ ( t ) dt size 12{f= Int rSub { size 8{`t rSub { size 6{1} } } } rSup {`t rSub { size 6{2} } } {Φ left (t right ) ital "dt"} } {}

If the flow is constant over the duration \(\Delta t\), it comes \(f=\phi\Delta t\). The quantity of light is expressed in joules \((J)\).