A class of students performed the heat transfer experiment shown in the picture. In the experiment, three plastic dishes were pa
rtially filled with equal amounts of dark soil, light soil, and water. Thermometers were placed in each dish, and the dishes were placed under a heating lamp. The substances were left under the heating lamp for ten minutes, and their temperatures were observed and recorded. After recording the temperatures of the substances as they were heating, the students turned the lamp off and recorded the temperatures of the substances as they cooled for ten minutes.
Which method of heat transfer is illustrated in this experiment? Explain your answer
Which method of heat transfer is illustrated in this experiment? Explain your answer
1 answer:
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Answer:
C) 7.35*10⁶ N/C radially outward
Explanation:
- If we apply the Gauss'law, to a spherical gaussian surface with radius r=7 cm, due to the symmetry, the electric field must be normal to the surface, and equal at all points along it.
- So, we can write the following equation:
- As the electric field must be zero inside the conducting spherical shell, this means that the charge enclosed by a spherical gaussian surface of a radius between 4 and 5 cm, must be zero too.
- So, the +8 μC charge of the solid conducting sphere of radius 2cm, must be compensated by an equal and opposite charge on the inner surface of the conducting shell of total charge -4 μC.
- So, on the outer surface of the shell there must be a charge that be the difference between them:
- Replacing in (1) A = 4*π*ε₀, and Qenc = +4 μC, we can find the value of E, as follows:
- As the charge that produces this electric field is positive, and the electric field has the same direction as the one taken by a positive test charge under the influence of this field, the direction of the field is radially outward, away from the positive charge.