Question 1
An electron (m = 9.1 × 10−31 kg, q = −1.6 × 10−19 C) starts from rest at point A and has a speed of 5.0 × 106 m/s at point B. Only electric forces act on it during this motion. Determine the electric potential difference VA−VB.
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−71 V
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+71 V
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−26 V
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+26 V
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−140 V
Question 2
An electron is released form rest in a region of space where a uniform electric field is present. Joanna claims that its kinetic and potential energies both increase as it moves from its initial position to its final position. Sonya claims that they both decrease. Which one, if either, is correct?
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Joanna, because the electron moves opposite to the direction of the field.
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Sonya, because the electron moves opposite to the direction of the field.
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Joanna, because the electron moves in the direction of the field.
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Sonya, because the electron moves in the direction of the field.
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Neither, because the kinetic energy increases while the electron moves to a point at a higher potential.