A radiometer can be used to determine the position of an approaching hot object by measuring the amount of irradiation it detect
s. Consider a radiometer placed at a distance H 5 0.5 m from the x-axis is used to measure the position of an approaching small blackbody object. If the radiometer is measuring 80% of the irradiation corresponding to the position of the object directly under the radiometer (x 5 0), determine the position of the object L.
Out of that list, the concave mirror is the only item that can concentrate sunlight and heat into a small area. But if you could get ahold of a convex lens, that would be even better.