In the activity of "Home Appliances Going to the Countryside", Xiaogang's family bought a micro-crossing furnace. (1) He observed the three legs of the power cord plug, as shown in the figure, and kne

In the activity of "Home Appliances Going to the Countryside", Xiaogang's family bought a micro-crossing furnace. (1) He observed the three legs of the power cord plug, as shown in the figure, and knew that they were slightly longer. Solution: (1) When the ground wire is inserted into the socket, the shell is grounded first, and when the socket is pulled out, the shell is separated from the ground wire.

(2)I= = =5A .

(3) Mass of 250ml water: m = ρ V =1.0×103kg/m3× 250x10-6m3 = 0.25kg, heat absorbed by water: Q=C Water m (t 2-t/. Power consumption: wtotal = pt =1100 w× 60s = 6.6×104j;

η= × 100%= × 100%= =92.3%。

(4) China's energy consumption is dominated by fossil energy. Encouraging the use of high-efficiency household appliances can effectively improve energy utilization, realize energy conservation and emission reduction, protect the environment and promote social sustainable development. (reasonable)