Oblique Beam Uses Normal Projection - Electromagnetic Radiation Pressure and Momentum Step by Step

An oblique absorber case uses an exact normal projection factor. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Oblique incidence uses a normal projection

The only allowed oblique factor in this book is an exact one-half.

I_\perp=6\cdot 1/2=3\ \text{W}/\text{m}^{2}

Projected irradiance sets projected pressure

The absorber pressure uses the projected normal irradiance.

p_\perp=1/2\ \text{Pa}