The average intensity of the solar radiation that strikes...

The average intensity of the solar radiation that strikes normally on a surface just outside Earth's atmosphere is $1.4 \mathrm{~kW} / \mathrm{m}^{2}$. (a) What radiation pressure $p_{r}$ is exerted on this surface, assuming complete absorption? (b) For comparison, find the ratio of $p_{r}$ to Earth's sea-level atmospheric pressure, which is $1.0 \times 10^{5} \mathrm{~Pa}$.

The average intensity of the solar radiation that strikes normally on a surface just outside Earth's atmosphere is $1.4 \mathrm{~kW} / \mathrm{m}^{2}$.
(a) What radiation pressure $p_{r}$ is exerted on this surface, assuming complete absorption? (b) For comparison, find the ratio of $p_{r}$ to Earth's sea-level atmospheric pressure, which is $1.0 \times 10^{5} \mathrm{~Pa}$.

Key Concepts

Atmospheric Pressure

Atmospheric pressure is the force per unit area exerted by the weight of the Earth's atmosphere on a surface. It is typically measured in Pascals (Pa), with sea-level pressure around 1.0 x 10^5 Pa. Comparing radiation pressure to atmospheric pressure provides a perspective on the relative magnitude of forces involved.

Speed of Light

The speed of light is a universal constant, approximately 3 x 10^8 meters per second, that plays a crucial role in the physics of electromagnetic radiation. It is central to the calculation of radiation pressure and appears in many fundamental equations in both classical and modern physics, linking energy, momentum, and the behavior of electromagnetic waves.

Solar Radiation Intensity

Solar radiation intensity refers to the amount of solar energy received per unit area per unit time, typically measured in kilowatts per square meter (kW/m²). It quantifies the energy available from the Sun’s radiation that reaches a surface and is a fundamental parameter in areas such as climatology, renewable energy, and astrophysics.

Radiation Pressure

Radiation pressure is the pressure exerted upon any surface due to the momentum carried by electromagnetic radiation. For complete absorption by a surface, the pressure is calculated using the formula p = I/c, where I is the radiation intensity and c is the speed of light. This concept illustrates the transfer of momentum from photons to a material upon interaction.

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