Một quả cầu kim loại bán kính 50 cm, đặt trong chân không, tích điện Q = 5.10 ^– 6 C. Tìm điện thế tại tâm quả cầu, chọn gốc điện thế ở vô cùng. a.180000 V b.0 V c.300 V d. 90000 V

Which surface feature of the moon is characterized by mountainous areas? terrae craters maria regolith

When a book falls from a shelf to the ground without anyone pushing on it, no work is done on the book. true or false

Glass is transparent to visibile light under normal conditions; however, at extremely high intensities, glass will absorb most of the light incident upon it. this works through a process known as multiphoton absorption. in this process, several photons are absorbed at the same time. if very intense light whose photons carry 2ev of energy is shined onto a material with a band gap of 4ev, that light can be absorbed through two-photon absorption, because two photons have the right amount of energy to bridge the band gap. what is the minimum number of photons of 800-nm light that are needed to equal or exceed the band gap of fused silica glass