Tính điện trường và điện thế của đoạn dây AB có độ dài 2a tích điện đều với mật độ điện tích dài lamđa ,gây ra tại điểm H trên đường vuông góc với trung điểm O một khoảng OH=h xét trường hợp đặc biệt khi a đến vô cùng

In positive numbers less than 1, the zeros between the decimal point and non zero are significant

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?

Afisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surface of the water. it takes a time of 2.20 s for the boat to travel from its highest point to its lowest, a total distance of 0.670 m . the fisherman sees that the wave crests are spaced a horizontal distance of 5.80 m apart. (a) how much is the wavelength? (b) find the period of the wave. (c) how fast are the waves traveling? (d) what is the amplitude a of each wave?