# Charging a rod Charge by conduction Charge by induction— induced charge.

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Charging a rod Charge by conduction Charge by induction— induced charge

A Hydrogen atom is composed of a nucleus containing a single proton about which a single electron orbits. The electric force between the two particles is 2.3 e 39 (that's 2.3 times 10 to the power 39) greater than the gravitational force. If we could adjust the distance between the two particles, can we find a separation at which the electric and gravitational forces are equal? explain your answer

●Yes, because F e =k e qq 0 /r 2, If we increase the distance, the electric force decreases, then eventually it equals to the gravitational force. ●Yes, as long as the gravitational force does not decrease at exactly the same rate as the electrical force, there should be a point at which they are equal. ●No. The gravitational and electric forces will never be equal because they are both inversely proportional to the square of the distance between the proton and election. Therefore, if you change the distance, both the gravitational and electric forces will change in equal proportion, and the electric force will still be 2.3 e 39 times greater than the gravitational force. A Hydrogen atom is composed of a nucleus containing a single proton about which a single electron orbits. The electric force between the two particles is 2.3 e 39 (thats 2.3 times 10 to the power 39) greater than the gravitational force. If we could adjust the distance between the two particles, can we find a separation at which the electric and gravitational forces are equal? explain your answer

+q 1 +q 2 Charge q 1 will feel a force due to charge q 2 and q 2 will feel a force due to q 1. Charge q 1 will move left and charge q 2 will move right. Charges q 1 and q 2 are placed in space. They are free to move.

Which force is larger? The force on q 1 due to q 2 or the force on q 2 due to q 1 The two forces are the same—Equal and opposite forces like gravity. +q 2 +q 1

M +Q m +q -q F F F The direction of F e is along a line connecting the two charges — but can attract or repel depending on the sign of the charges.

Electric Charge Like charges repel. Unlike charges attract.

Three balls are suspended from thin insulating threads. Onto each ball is transferred some charge. It is found that balls 1 and 2 repel each other and that balls 2 and 3 also repel each other. What can we conclude about the charges on the balls? Explain your answer. ●If the balls repel each other they must have the same charge. 1 and 2 are the same, 2 and 3 are also the same, so all three balls must have the same charge. However, we can't say whether that charge is positive or negative just from this information.

Discussion question: Three rods are suspended from thin insulating threads. It is found that rods 1 and 2 attract each other and that rods 2 and 3 repel each other. What can we conclude about the charges on the rods? 1.1 and 3 carry charges of opposite sign. 2.1 and 3 carry charges of the same sign. 3.All three carry charges of the same sign 4.One of the objects carries no charge. 5.We need to do more experiments to answer the question above.

Discussion question: Three charges are placed as shown. Charges A and B are held fixed in place. What direction is the force on C? A. B. C. D. E. Zero magnitude – no direction AB C +q -q

Two charges are placed as shown. What direction is the electric force on a positive charge at point A? A. B. C. D. E. Zero magnitude – no direction A +q

Which vector has a greater magnitude? What direction is the net force? What if I make q 1 negative. Then what direction is the net force?

What is the z component of a unit vector in the direction of vector A = (3, -2, 2) m ? (magnitude only) A.3.000 m B.2.000 m C. 0.7276 m D. 0.4851 m E. 1.000 m

Electric Field The direction of the Electric field is the direction of the force on a positive point charge at a given point. Force is a vector Electric field is a vector q 1 feels a force due to an electric field produced by q 2.

Three charges are placed as shown. Charges A and B are held fixed in place. What direction is the electric field at C? A. B. C. D. E. Zero magnitude – no direction AB C +q -q

Math review In packet –Study formulas and chapter summaries –Study “What does it mean to integrate?” Next three class periods we will do a lot of math review. The math review test starts next Wednesday

Answers 10-5 11-b 12-b 14-d 16-b

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