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Item 1:

In some books a causal model for an electric circuit is presented as shown in the following picture.

On the line from the battery to the motor the electrons carry the energy to drive the motor. On the line back to the battery, the electrons are without energy and need to be reloaded.

Which of the following statements is correct?

• 1) This model for the electric current is acceptable. It corresponds with the definition: voltage or potential difference = energy per charge
• 2) This model is only partly acceptable because the electrons on their way back to the battery are not completely without energy as shown in the figure but rather they have some energy. However, they have less energy than on their way to the motor.
• 3) This model is not acceptable because in a good model the electrons in both lines should play equally important roles in respect to energy and to drive the motor.

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