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Physics Assessment
Honors Physics Final EXAM
| Term | Definition |
|---|---|
| Electrostatics | The study of electric charge at rest (not in motion, as in electric current) |
| Conservation of charge | Electric charge is neither created nor destroyed. The total charge before an interaction equals the total charge after |
| Coulomb's law | The relationship between electrical force, charge, and distance. If the charges are alike in sign, the force is repulsive; if the charges are unlike, the force is attractive |
| Coulomb | The SI unit of electrical charge. One coulomb is equal to the total charge of 6.25 x 10^18 electrons |
| Conductor | Any material having free charged particles that easily flow through it when an electric force acts on them |
| Insulator | A material without free charged particles and through which charge does not easily flow |
| Semiconductor | A material with properties that fall between a conductor and an insulator and whose resistance can be affected by adding impurities |
| Superconductor | A material that is a perfect conductor with zero resistance to the flow of electric charge at low temperatures |
| Charging by Contact | Transfer of electric charge between objects by rubbing or simple touching |
| Charging by Induction | Redistribution of electric charges in and on objects caused by the electrical influence of a charged object close by but not in contact |
| Electrically Polarized | Term applied to an atom or molecule in which the charges are aligned so that one side has a slight excess of positive charge and the other side a sleight excess of negative charge |
| Electric field | Defined as electric force per unit charge, it can be considered to be an "aura" surrounding charged objects and is a storehouse of electric energy. About a charged point, the field decreases with distance according to the inverse-square law |
| Electric potential energy | The energy a charged object possesses by virtue of its location in an electric field |
| Electric potential | The electric potential energy per unit of charge, measured in volts, and often called voltage |
| Capacitor | An electrical device that stores electric charge and energy |
| Electric Current | the flow of electric charge that transports energy from one place to another. |
| Electrical Resistance | The property of a material that resists electric current. Measured in ohms |
| Ohm's Law | The statement that the current in a circuit varies in direct proportion to the potential difference or voltage across the circuit and inversely with the circuit's resistance |
| Direct Current | Electrically charged particles flowing in only one direction |
| Alternating Current | Electrically charged particles that repeatedly reverse direction, vibrating about relatively fixed positions |
| Series Circuit | An electric circuit in which electrical devices are connected along a single wire such that the same electric current exists in all of them |
| Parallel Circuit | An electric circuit in which electrical devices are connected in such a way that you only have to go through one to complete the circuit and if one load goes out, the circuit will still work |
| What are the three main forms of transferring charge? | Friction, induction, and conduction |
| What are the Laws of Static Electricity? | Like charges repel, opposite charges attract, and neutral objects are attracted to charged object |
| What are examples of insulators? | rubber, wood, concrete, foam, cotton, wool, silk, glass |
| What are examples of conductors? | salt water, platinum, copper, and iron |
| Electroscope | A device that determines if an object is charged or not |
| How do you shield an object? | Surrounding an object with material you can charge |
| When do electrons flow? | When there is a potential difference |
| Through what pathway in the body will a current do the most damage? | Through the heart |
| Which has less resistance thick or thin wires? | Thick wires |
| Which has less resistance wet or dry fingers? | Wet fingers |
| Which has less resistance warm or cool wires? | Cool wires |
| (Calculator) A circuit that contains 100 ohms resistance has a current of two amperes. What is the applied voltage? | 200 Volts |
| (Calculator) A circuit has an applied voltage of 200 volts that causes a 50 mA current to flow. What is the circuit resistance? | 4000 Ohms |
| (Calculator) If applied voltage is 400 volts and resistance is 20,000 Ohms, what is the value of I? | .02 Amperes |
| Electrical charge can be _____ or _____ | negative, positive |
| The _____ charge comes from _____ in the atom | negative, electrons |
| _____ charges repel and _____ charges attract | like, opposite |
| The attraction between 2 objects depends on what 2 things according to Coulomb's law? | Size of the charge and the distance |
| Why are Superconductors important? | When cooled to very low temperatures, electrical resistance disappears |
| The arrows used to draw electric fields point _____ from a positive object and _____ for a negative object | outward, inward |
| The number of arrows in an electric field show the _____ of the field and the arrows indicate the _____. As the arrows move farther apart, the field becomes _____ | strength, charge, weaker |
| Why can't we shield from gravity? | Gravity only attracts and there are no repelling parts of gravity to offset attracting parts |
| Gravity only attracts and there are no repelling parts of gravity to offset attracting parts | A laboratory instrument that builds up a charge |
| What are the four parts of a circuit? | Source, switch, load, and wires |
| Batteries, generators, and power plants are all examples of _____ _____ | Voltage sources |
| __________ opposes the flow of charge | Electrical resistance |
| What really does the damage in an electric shock? | The current |
| How many Amperes does it take before your heart can contract and eventually lead to death? | .065 Amps |
| From where does direct current usually come from? (example) | A battery |
| What are the benefits to a series circuit? | They are simple and do not use a lot of wire=cheap |
| What are the drawbacks to a parallel circuit? | They are costly to make and are complicated |
| How do short circuits form? | When an electric current goes through a circuit and does not meet any resistance in the form of loads or resistors. |
| Why are short circuits so dangerous? | When a short circuit receives no resistance, the circuit may overheat and melt which could cause severe burns |
| magnetic force | Between magnets, it is the attraction of unlike magnetic poles for each other and the repulsion between like magnetic poles |
| magnetic field | the region of magnetic influence around a magnetic pole or a moving charged particle |
| magnetic domains | clustered regions of aligned magnetic atoms |
| electromagnet | a magnet whose field is produced by an electric current, It is usually in the form of a wire coil with a piece of iron inside the coil |
| electromagnetic induction | the induction of voltage when a magnetic field changes with time. If the magnetic field within a closed loop changes in any way, a voltage is induced in the loop |
| Generator | an electromagnetic induction device that produces electric current by rotating a coil within a stationery magnetic field. A generator converts mechanical energy to electrical energy |
| Transformer | A device for transferring electric power from one coil of wire to another, by means of electromagnetic induction, for the purpose of transforming one value of voltage to another |
| Power into primary=. . . | Power into secondary! |
| Changing the magnetic field intensity in a closed loop of wires induces . . . | both current and voltage |
| A transformer transforms. . . | Voltage |
| If the north pole of one magnet is brought near the south pole of another magnet, the poles will. . . | attract to each other |
| In order to make an electromagnet, you need a . . . | battery, some wire, and a nail |
| Which pole of a compass needle points to a south pole of a magnet? | north pole |
| True or False: Because magnetism is slightly different from electrostatics, magnetic fields do not exist. | False |
| True or False: Spinning electrons themselves are small magnets. | True |
| True or False: Magnetic domains are regions in a material where clusters of atoms are randomly magnetized. | False |
| Where are the magnetic field lines closest together in the magnetic field surrounding a bar magnet? | At the poles! |
| In a transformer, the primary coil has twice as many loops as the secondary coil. This is a __________ transformer. | Step-Down |
| What is the working principle behind an electric generator? | Spinning a coil of wire near a permanent magnet induces a current |
| The electrical force between charges is strongest when the charges are. . . | close together |
| Rub electrons from your hair with a comb and the comb becomes. . . | negatively charged |
| If you comb your hair and the comb becomes positively charged, then your hair becomes. . . | negatively charged |
| An electroscope is charged positively as shown by foil leaves that stand apart. As a negative charge is brought close to the electroscope, the leaves. . . | fall closer together |
| An iron nail is more strongly attracted to which pole? | North or South pole - no difference really. |
| True or False: Electric power can be transmitted from one place to another without the need for connecting wires in between | True! |
| A step-up transformer increases what? | Voltage |
| A step-up transformer has a ration of 1 to 10. Neglecting slight losses, if 100W of power goes into the primary coil, the power coming from the secondary coil is. . . | 100 W |
| The space around a magnet contains what? | A magnetic field |
| Is magnetism related to electricity? | Yes! |
| What condition is necessary for an electric charge to have a magnetic field around it? | It must be moving! |
| Is it correct to say that every electron spinning on its axis is a tiny magnet? | Yes |
| Why are most materials not magnetic? | The magnetic fields produced by the electron spin is canceled |
| All pieces of iron have magnetic domains, why are most iron nails not magnetic? | Their domains are randomly oriented, canceling out most magnetic forces |
| What amount of current will produce a slight tingling sensation? | 1 mA or 0.001 A |
| What amount of current will make your chest muscles paralyzed and you can't breathe? | 18 mA or 0.018 A |
| What amount of current will make you not able to let go? | 10-16 mA or 0.01-0.016 A |
| What amount of current can make your heart contract and be fatal? | 65 mA or 0.065 A |
Created by:
mattneider
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