Cho mạch điện có điện chở R =50 , cho dòng điện có cường độ 1,8A qua điện trở . a) tính hđt của nguồn điện . b) thay R bằng R' khi đó cđdđ qua R' giảm ba lần tính R' . c) thay R băng R'' = 15 khi đó cđdđ qua R'' là bao nhiêu?

Amoving company collects data about couches they move and displays the data in a table. the force along the ramp, the angle of the ramp, and the height the couch is raised to are shown. which statements correctly compare the work done to move the couches? check all that apply. the same amount of work is done for couches 1 and 3. the same amount of work is done for couches 2 and 3. the work for couch 1 is greater than the work for couch 2. the work for couch 2 is less than the work for couch 3. the work for couch 3 is greater than the work for couch 1. the work for couch 2 is greater than the work for couch 1.