How many soil moisture sensors are needed to measure an area of 1500km^2, in which the area is high infiltrated?Compare the light gathering power of a 1 meter diameter telescope to that of the human eye ,which has a diameter of roughly 2.5 centimeters. How many times more light can the telescope gather than the human eye?

2) Which of the following types of light (or, electromagnetic radiation) has the longest wavelength: visible light, infrared, ultraviolet, gamma rays or X-rays?

3) What is an element? Name five different elements, and state what makes them different from each other.

4) A spectrum of one star in the Big Dipper shows that a certain spectral line has a wavelength of 486.112 nm. But the rest wavelength of this same spectral line is 486.133 nm. Is this star moving towards us or away from us? How fast is this star moving?

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