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RAD150 Chapter 4
| Question | Answer |
|---|---|
| Define electrostatics | study of stationary electric charges |
| What is the smallest unit of electric charge? | electron |
| What is the fundamental unit of electric charge? | coulomb |
| 1 coulomb=? | 6.3x10^18 electron charges |
| What is Coulomb's Law? | electrostatic force directly proportional to product of charges & inversely proportional to square of the distance F=k(Q1Q2)/d^2 |
| Define electrodynamics | study of electric charges in motion |
| What is current and how is it measured? | number of electrons flowing; amperes |
| 1 ampere=? | 1 coulomb of electrons flowing through a conductor per second |
| Electromotive force refers to ________ | electric potential |
| Define electric potential | the force with which electrons travel |
| How is electric potential measured | volts |
| 1 volt=? | 1 joule per coulomb |
| Resistance depends on what 4 factors? | material's conductivity, length, diameter and temperature |
| What are the 4 electric states of matter? | insulator, semiconductor, conductor, superconductor |
| What is an example of an insulator? | glass, clay, rubber |
| What is an example of a semiconductor? | silicon, germanium |
| What is an example of a conductor? | copper, aluminum, water |
| What is an example of a superconductor? | niobium, titanium |
| What is Ohm's Law? | V=IR (voltage=current X resistance) |
| What is electric power? How is it measured? | the rate at which energy moves or is used; watts |
| 1 watt=? | 1 ampere current flowing through 1 volt electric potential |
| What is the formula for power? | P=IV |
| What are the 3 classifications of magnets? | natural, artificial permanent, electromagnet |
| What are the 4 magnetic states of matter? | nonmagnetic, diamagnetic, paramagnetic, ferromagnetic |
| Define nonmagnetic & give an example | unaffected by magnets; wood, glass |
| Define diamagnetic & give an example | weakly repelled & can't be magnetized; water, plastic |
| Define paramagnetic & give an example | weakly attracted to magnets; gadolinium, platinum, aluminum |
| Define ferromagnetic & give an example | can be strongly magnetized; iron, nickel, cobalt |
| Magnetic force is proportional to _______. | the product of the pole strengths divided by the distance between them |
| What is flux density and how is it measured? | magnetic field strength in teslas |
| What is a magnetic dipole? | small magnet created by electron orbit |
| What is a magnetic domain? | accumulation of atomic magnets with aligned dipoles |
| What is magnetic permeability? | the ability of a material to attract lines of magnetic field intensity |
| Define induction | the process of making ferromagnetic material into a magnet |
| A coil of wire is called a _____. | solenoid |
| What did Oersted's experiment reveal? | an electric current is induced if part of a circuit is in a changing magnetic field |
| Faraday's Law states that the magnitude of an induced current depends on what 4 factors? | strength of magnetic field, velocity of field moving past conductor, angle between conductor and field, number of turns in conductor |
| A coil of wire in a generator is called the _____. | armature |
| How does a generator work? | an armature is placed between opposing magnetic poles, mechanically turning the armature induces an electric current within the magnetic field |
| What are the 3 types of transformers? | closed-core, shell-type, autotransformer |
| What is the transformer law? | the change in voltage is directly proportional to the turns-ratio of the coils Vs/Vp=Ns/Np |
| A turns ratio >1 is a _______ transformer, a turns ratio <1 is a _______ transformer. | step-up; step-down |
| As voltage in a transformer changes, _____ changes inversely. | current |
| Total resistance in a series circuit=? | sum of individual resistances |
| Total current in a series circuit=? | current through each element |
| Total voltage in a series circuit=? | sum of individual voltages |
| Total resistance in a parallel circuit=? | reciprocal of sum of 1/each individual resistance |
| Total current in a parallel circuit=? | sum of currents through each element |
| Total voltage in a parallel circuit=? | voltage across each element |
| A step-up transformer will have _____ voltage and _____ current in the second coil compared to the first. | higher; lower |
| A step-down transformer will have _____ voltage and _____ current in the second coil compared to the first. | lower; higher |
Created by:
SCash21
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