Un calefactor eléctrico de 1kW tiene resistencias calefactoras que están "al rojo" a 900°C. Suponiendo que el 100% de la potencia útil se deba a la radiación y que las resistencias actúen como cuerpos negros. Hallar el área efectiva de la superficie radiante. Considerar que la temperatura ambiente es de 20°C.

What is the magnitude of the resultant vector round your answer to the nearest tenth

Two resistors r1 and r2 may be connected either in series or parallel across an ideal battery with emf ε. we desire the rate of energy dissipation of the parallel combination to be 8.75 times that of the series combination. if r1 = 105 ω, what are the (a) smaller and (b) larger of the two values of r2 that result in that dissipation rate?

Place several e-field sensors at a few points on different equipotential lines, and look at the relationship between the electric field and the equipotential lines. which statement is true? 1-at any point, the electric field is perpendicular to the equipotential line at that point, and it is directed toward lines of higher voltages. 2-at any point, the electric field is perpendicular to the equipotential line at that point, and it is directed toward lines of lower voltages. 3-at any point, the electric field is parallel to the equipotential line at that point.