E.S. fundamental Qn. & Ans

A flash of lightning is nature’s most Spectacular static electricity effect!!!!!-------M.A.Mumeed Electric charge is an important property of nature. Some particles, for example the proton, have a positive charge. Some particles, like the electron, have a negative charge. You might have noticed, I said some particles……… can you name any of the other????? However, in 1960s, small particles called quarks were discovered. Charge on the proton = +e Charge on the electron = -e What is “ e “ ???? Name a particle of electromagnetic radiation which has no electrical charge at all?? Saying Neutron has no charge at all is WRONG!!!!!! Neutrons have no overall charge. They contain three quarks whose charges cancel each other!! 1. Two neutral conducting pop cans are touching each other. A positively charged balloon is brought near one of the cans as shown below. The cans are separated while the balloon is nearby, as shown. After the balloon is removed the cans are brought back together. When touching again, can X is ____. a. positively charged b. negatively charged c. neutral d. impossible to tell 2. Two neutral conducting pop cans are touching each other. A positively charged glass rod is brought near Can X as shown below. Which of the following occur as the glass rod approaches Can X? List all that apply. a. Electrons jump from the glass rod to can X. b. Electrons jump from the glass rod to can Y. c. Electrons jump from can X to the glass rod. d. Electrons jump from can Y to the glass rod. e. Protons jump from the glass rod to can X. f. Protons jump from can X to the glass rod. g. ... nonsense! None of these occur. Q3:  A positively charged balloon is brought near a neutral conducting sphere as shown below. While the balloon is near, the sphere is touched (grounded). At this point, there is a movement of electrons. Electrons move ____ . a. into the sphere from the ground (hand) b. out of the sphere into the ground (hand) c. into the sphere from the balloon d. out of the sphere into the balloon e. from the ground through the sphere to the balloon f. from the balloon through the sphere to the ground g. .... nonsense! Electrons do not move at all. Q4: A negatively charged balloon is brought near a neutral conducting sphere as shown below. As it approaches, charge within the sphere will distribute itself in a very specific manner. Which one of the diagrams below properly depicts the distribution of charge in the sphere? Q5:  Two charged objects have a repulsive force of 0.080 N. If the charge of one of the objects is doubled, then what is the new force? Q6: Two charged objects have a repulsive force of 0.080 N. If the distance separating the objects is doubled, then what is the new force? Q7: Two charged objects have a repulsive force of 0.080 N. If the charge of both of the objects is doubled and the distance separating the objects is doubled, then what is the new force? Q8: A positively charged object with a charge of +85 nC is being used to balance the downward force of gravity on a 1.8-gram balloon that has a charge of -63 nC. How high above the balloon must the object be held in order to balance the balloon? (NOTE: 1 nC = 1 x 109 C) 1-Answer: c. Neutral When the balloon is near, electrons leave Can Y and enter Can X. Overall, the two cans are neutral; yet as individual cans, Can X is negatively charged and Can Y is positively charged. When the cans are touched again, the excess electrons in Can Y return to Can X. Once more, the overall charge on the system of two cans is zero - the system is neutral. 2-Answer: g Since contact is not made between the glass rod and Can X, there is no transfer of electrons between them. And of course, there is never a transfer of protons in electrostatic experiments. The glass rod simply induces the movement of electrons from Can Y to Can X, causing Can X to acquire a negative charge and Can Y to acquire a positive charge. 3-Answer: A Since the balloon is not contacted to the sphere, electrons do NOT move between the balloon and the sphere (ruling out choices c, d, e, and f). The presence of the positive balloon draws electrons from ground to the sphere. This is the principle of opposites attract. 4-Answer: C Since the balloon is charged negatively, electrons in the sphere will be repelled and move from the left side to the right side of the sphere. As a result, the left side of the sphere will have an excess of positive charge (since it lost electrons) and the right side will have an excess of negative charge (since it gained the electrons) 5-Answer: 0.160 N Explanation: Electrostatic force is directly related to the charge of each object. So if the charge of one object is doubled, then the force will become two times greater. Two times 0.080 N is 0.160 N. 6-Answer: 0.020 N Explanation: The electrostatic force is inversely related to the square of the separation distance. So if d is two times larger, then F is four times smaller - that is, one-fourth the original value. One-fourth of 0.080 N is 0.020 N. 7-Answer: 0.080 N Explanation: The electrostatic force is directly related to the product of the charges and inversely related to the square of the separation distance. Doubling both of the charges would serve to quadruple the force. Doubling the distance would serve to reduce the force by a factor of four. The combined affect of these two variations would be to not change the force at all; it remains as 0.080 N. 8-Answer: 0.155 meters Given: Q1 = +8.5 x 10-8 C Q2 = -6.3 x 10-8 C m = 0.0018 kg Use the mass to determine the force of gravity (m • g). The force of gravity on the balloon is 0.0176 N. Thus, the upward electrical force is 0.0176 N. Now that F, Q1, and Q2 are known, Coulomb's law can be used to determine the distance d in the equation. Algebraic rearrangement leads to d = Sqrt [ (Q1• Q2) / F ]. Substitution leads to the answer. Electrostatics 1 - M. Abdul Mumeed. +966507433412 4 © Md. Abdul Mumeed, Senior Secondary Teacher in PHYSICS at I. I. School, Riyadh, K.S.A.