Studying the chromosphere and corona: Consider observations of the solar chromosphere and corona
What are the principle difficulties in observing them in X-ray, ultraviolet, and in visible light? What could be done to circumvent those difficulties?
X-ray light and ultraviolet light do not penetrate the Earth's atmosphere, but we can solve this problem by building space telescopes. In visible light, the photosphere is much brighter than the corona and chromosphere, but we can block the photosphere's light with something inside our telescopes or observe the sun during a solar eclipse.
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Moment of Inertia: A potter's wheel has the shape of a solid uniform disk of mass 7.0 kg and radius 0.65 m. It spins about an axis perpendicular to the disk at its center. A small 2.1 kg lump of very dense clay is dropped onto the wheel at a distance 0.41 m from the axis. What is the moment of inertia of the system about the axis of spin?
A. 1.8 kg ? m2 B. 1.5 kg ? m2 C. 0.40 kg ? m2 D. 2.5 kg ? m2
A particle (m = 2.0 mg, q = -5.0 mC) has a speed of 30 m/s at point A and moves (with only electric forces acting on it) to point B where its speed is 80 m/s. Determine the electric potential difference VA - VB
a. -2.2 kV b. +1.1 kV c. -1.1 kV d. +2.2 kV e. +1.3 kV
Equipotentials are lines along which
a. the electric field is constant in magnitude and direction. b. the electric charge is constant in magnitude and direction. c. maximum work against electrical forces is required to move a charge at constant speed. d. a charge may be moved at constant speed without work against electrical forces. e. charges move by themselves.
_________is the increase in conductivity that results when photons excite electrons in a semiconductor or insulator into the conduction band.
Fill in the blank(s) with the appropriate word(s).