In general, good observatory sites are at high altitude, with clear skies and a stable atmosphere. more specifically, different site characteristics are important for different applications. some of the things that matter include: clear sky fraction: how often the atmosphere is non-cloudy median seeing humidity temperature isoplanatic patch size wind speed light pollution considering those characteristics, briefly explain which are likely to be most important for the following observations, and why? a) wide field imaging in visible light b) adaptive optics imaging in the near-infrared ~1 um c) mid-infrared (10um) imaging

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation:

3. dark matter

empty space could also be a simple vacuum