Hai bóng đèn có hiệu điện thế định mức là U1= 1,5 V và U2= 6 V. Khi hai đèn này sáng bình thường thì chúng có điện trở tương ứng là R1= 1,5 Ω và R2= 8 Ω. Cần mắc hai đèn này cùng với một biến trở vào hiệu điện thế U = 7,5 V theo sơ đồ như hình vẽ.Tính điện trở của biến trở khi đèn sáng bình thường

An automobile steering wheel is shown. what is the ideal mechanical advantage? if the ama is 8, what is the efficiency of the steering wheel?

Ametal ring 4.20 cm in diameter is placed between the north and south poles of large magnets with the plane of its area perpendicular to the magnetic field. these magnets produce an initial uniform field of 1.12 t between them but are gradually pulled apart, causing this field to remain uniform but decrease steadily at 0.240 t/s . (a) what is the magnitude of the electric field induced in the ring? (b) in which direction (clockwise or counterclockwise) does the current flow as viewed by someone on the south pole of the magnet?

Jenny wants to test the electrical conductivity of two substances dissolved in water. she is preparing the containers for the experiment. which factor is most important for her to control? a) volumes of the solutions b) appearance of the solutions c) temperatures of the solutions d) concentrations of the solutions