☰ Contents · Physics

Work and power of current

Lessons 30–31 · 2 lessons · P.Q. Habibullayev, A. Boydedayev, A.D. Bahromov, J.E. Usarov, K.T. Suyarov, M.K. Yuldasheva. Physics, textbook for Grade 8 of general secondary schools, revised and enlarged 3rd edition. “O‘qituvchi” Publishing and Printing Creative House, Tashkent, 2019
Answers are for parents and teachers.
1
U = 6 V, I = 0.5 A, t = 100 s. The work of the current in J?
2
A heater has R = 50 Ω and I = 2 A. Its power in W (P = I²R)?
3
A device at U = 12 V has R = 6 Ω. Its power in W (P = U²/R)?
4
A 1500 W device runs 2 hours. How many MJ of energy does it use? (1 kW·h = 3.6 MJ)
5
Why must you not experiment on your own with devices connected to the mains?