The current through a certain heater wire is found to be fairly independent of its temperature. If the current through the heater wire is doubled, the amount of energy delivered by the heater in a given time interval will(a) increase by a factor of two. (b) decrease by a factor of two. (c) increase by a factor of four.(d) decrease by a factor of four. (e) increase by a factor of eight.

(c) increase by a factor of four

Explanation:

energy = power x time, and power = resistance x current ^2. 2^2 = 4.

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.