Solar Irradiance Experiment

First, solar irradiance is really just a measure of the energy in
sunlight.

Answering the following questions shows how you can use a few simple
measurements to determine the solar irradiance (the questions are
listed on p. 63 in the photocopied class notes).

1. What are the units of solar irradiance, S:

basically how many calories of energy strike a 1 cm by 1 cm square
area
every minute.

2. How much energy will a collector of area A collect in
time delta t?

An aluminum plate with large area will collect more energy than a
plate
with small area. The longer you leave the plate in the sun the
more energy it will collect.

3. What temperature change, delta T, will delta E cause?

This is an equation that we covered early in Chapter 2 (we were more
worried about energy being absorbed by water and soil):

4. Replace delta E in (3) with the the equation in (2)

5. Solve this equation for solar irradiance, S.

There is the equation you need. If you know the mass of the
aluminum plate, its crossectional area, the specific heat of aluminum,
and measure how quickly the block warms with time, you can calculate
the solar irradiance.