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Description
Flashcards by Veronica Martinez, updated more than 1 year ago
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Created by Veronica Martinez
almost 9 years ago
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| Question | Answer |
| ELECTRIC CHARGE | -Fundamental property of matter. -Many particles including the electron and proton carry it. -Comes in two varieties, positive and negative. -Most charged particles carry exactly one elementary charge, e, either positive or negative. -In a closed system is conserved, the algebraic sum of charges remains unchanged. [True even if new particles are created or destroyed.] -SI unit is coulomb (C), equal to approx 6.25 e 18 elementary charges. |
| Plastic Rods | |
| Glass Rod | |
| Proton | Carries exactly +e |
| Electron | Carries exactly -e |
| e | 1.6x10^(-19)C |
| Atom | Most of the volume is occupied sparsely by electrons. Electrons move, protons don't. |
| Atomic Charge | Protons and electrons account for it. |
| Nucleus | Tiny compares with rest of the atom, contains over 99.9% of the atom's mass. |
| Positive Net Charge | Fewer electrons than protons. |
| Negative Net Charge | More electrons than protons. |
| Charging by Induction (steps) | 1. Uncharged metal ball 2. Neg. charge on rod repels electrons, creating zones of negative and positive induced charge. 3. Wire lets electron build-up (induced neg. charge) flow into ground. 4. Wire removed: ball now has an electron deficient region of positive charge. 5. Rod removed; pos. charge spreads over ball |
| Charging by Induction (definition) | The process in which a charged object can give another object a charge of opposite sign without losing any of its own charge is called induction. |
| Electric Force | -Makes like charges repel, and opposite charges attract. -Depends on the product of the two charges and inverse square of the distance between them. -Mathematically, described by Coulomb's law. |
| Coulomb's Law 1/2 | |
| Coulomb's Law 2/2 | |
| Superposition Principle | -Means the force two charges exert on a third force is just the vector sum of the forces from the two charges, each treated without regard to the other charge. -Obeyed by the electric force. |
| Electric Field | -At a point in space is the force per unit charge q placed at that point would experience: E=F/q -The force on a charge q in an electric field E is F=qE -Field lines always point away from + charges and toward - charges. -At each point in space, the electric field vector is tangent to the field line passing through that point. |
| Field Lines for Simple Charge Distributions | |
| Fields of Point Charges | Radial, outward for a positive charge and inward for negative charge. E=kq/(r^2) |
| Charge Distributions | Superposition principle shows that the field due to a charge distribution is the vector sum of the fields of the individual charges. |
| Electric Dipole IMPORTANT Charge Distribution | -Consists of two point charges of equal magnitude but opposite signs, held a shor distance apart. -Electrically neutral, but the separation of its charges results in an electric field. -Many charge distributions, especially molecules, behave like electric dipoles. -The product of the charge separation is the dipole moment: p=qd -Far from the dipole, its electric field falls off as the inverse cube of the distance. |
| Conductors | Materials in which charge is free to move. |
| Insulators | -Materials in which charge isn't free to move. -Alignment of molecular dipoles reduces an externally applied field. |
| Dielectrics | -Materials generally contain molecular dipoles, which experience torques and forces in electric fields. |
| Induced Dipole Moments | Even if molecules aren't intrinsically dipoles, the acquire IDM as a result of electric forces stretching the molecule. |
| Motion of Point Charges in Electric Fields | When a particle that has a charge q is placed in an electric field E, it experiences a force qE. If the electric force is the only force acting on the particle, the particle has acceleration. |
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