Physics Exam 3 Tested Questions with Correct Answers Guaranteed to get an A (2025 Version).

Physics Exam 3 Tested Questions with Correct Answers Guaranteed to get an A (2025 Version). In its normal state, an object has no charge (is neutral). If the object obtains a negative charge, this happens because the object has ___________ gained an excess of electrons - electrons moved to the object Coulomb's equation for force in electricity (electrical force) between two charged objects is: F = K x (q1 x q2) / (d squared) where q1 and q2 are charges and d is the distance between the two charged objects If the distance between the objects is increased so that the new distance is 4 x the original distance, this will make the electrical force between the two objects ____________ as strong as it was originally. 1/16 x If an atom has a negative charge, it is called a (an) _____________ . Charge is measured in _____________ . ion / coulombs Charge is never just gained or lost. Even though an object may gain or lose charge in an exchange, all charges are always accounted for. Point: Electrons and protons are never created or destroyed in a charge transfer process! True A material which holds electrons tightly is a (an) ____________ and a material in which electrons are able to move freely is a (an) ____________. Current flows more easily through a (an) ____________ . insulator / conductor / conductor When two objects make physical contact they may become charged as charge moves from one to the other. This is called ______________ . If an object becomes charged (polarized) due to approach of a nearby charged object, but no contact is made, this is called _____________ . conduction / induction A Faraday Cage is a particular type of electric _____________ and the electric field inside the cage is ____________ . shield / 0 A gold leaf electroscope is used to detect presence of ______________ . When the leaves are spread far apart this indicates that there is a ______________ . an electric field / strong charge present You walk across a rug with your sneakers on (rubber souls!) and then as you touch a metal door handle you experience a shock! What just happened? You removed electrons from the rug because your sneakers were acting as a (an) __________ . When you made contact with the metal door handle, negative charge (because of the electrons you picked up from the rug) moved to the door handle by __________ insulator / conduction An electric field is measured in electric force per unit charge. It is caused by presence of electric charges. Conventionally, the direction of the field is the direction a ____________ test charge would be forced to move, when in the field. In reality it is the ___________ charges that move in an electric field. positive / negative A volt is _____________ . A capacitor, when connected to a battery, stores voltage by placing ____________ charges a short distance apart. potential energy / opposite A negatively charged rod is brought close to a neutral (no charge) table top. The _____________ in the table move ______________ the rod. electrons / away from A negatively charged rod is brought close to a neutral (no charge) table top. The table has a charge focused at the end of the table close to the rod. This result is called charge polarization. True Batteries produce ____________ current and the current flowing through a normal house circuit is ____________ current. DC / AC Several items are required for construction of a practical circuit? Which of the following items is/are necessary. a. voltage source b. closed conducting path c. current d. a and b e. a, b, and c d. a and b Which of the following causes a decrease in resistance to current flow? a. replacing a wire with a wider (thicker) wire b. replacing a wire with a longer wire c. replacing a wire with a hot (warmer temperature) wire d. a and c e. b and c a. replacing a wire with a wider (thicker) wire When the voltage applied to a circuit is decreased, if nothing else in the circuit changes, the current through a light bulb in the circuit will ____________ and the brightness of the bulb will ____________ . decrease / decrease The change in brightness of the bulb in the previous question, would be caused by the change in _____________ current When two bulbs are connected in series they will always have the same _____________ but they may have different _____________ . currents / voltage drops Two bulbs are connected in series to a battery. The resistance of bulb A = 3 x the resistance of bulb B. The current through bulb A is ____________ the current through bulb B. equal to As more resistors (light bulbs in this case) are added to a series circuit, the total resistance of the circuit _____________ . The light bulb with the greatest resistance will experience the ___________ voltage drop. increases / greatest When two bulbs are connected in a parallel circuit, they will always have the same ___________ but may have different _____________ . voltage drops / currents The points in a circuit where wires join together are called ____________ and the different paths which exist in a parallel circuit are called _____________ . junctions / branches As more branches (with resistors, e.g. a light bulb in each branch) are added in a parallel circuit, the total resistance of the circuit ____________ and the total current in the circuit ____________ . decreases / increases Four lightbulbs are connected in a parallel circuit. If one of the bulbs burns out (i.e. the wire inside the bulb separates), the other bulbs in the other parallel pathways will _____________ . This happens because the other pathways in the circuit are ____________ each other. continue shining / independent of Two circuits with two light bulbs each, use identical resistors (light bulbs), have identical same length wires, and use identical power sources (identical batteries). One circuit is a series circuit and the other is a parallel circuit. The total resistance in the parallel circuit will be __________ than the total resistance in the series circuit and the total current in the parallel circuit will be ___________ than the total current in the series circuit. less / greater There will never be any current flow in any situation unless there is a voltage applied. True According to our text (ch 22.5) good conductors of electrical current are also good _________ conductors. heat According to our text (ch 22.2), all atoms have the same electrons (i.e. same type, all electrons in a Helium atom are the same as those in an Oxygen atom - electrons are the same, in different atoms). True According to our text (ch 22.2), most atoms have the same number of electrons and protons. Each proton has a mass that is about ____________ x the mass of an electron. Each electron carries a negative charge. Each proton carries a positive charge that is ____________ and opposite to the charge of the electron 1800/equal to A circuit has a 4 Ohm resistor (light bulb) with a 12 amp current flowing through it. The battery providing voltage must be a __________ volt battery 48 What is the current (amps) through a 2 Ohm resistor connected to a 6 volt battery? 3 amps What is the power (watts) provided by the battery in the previous question? (reminder: P = IV) 18 watts The total resistance of a 12 Ohm and an 18 Ohm resistor connected in series is ____________ (Ohms). 30 Ohms A series circuit has 3 resistors, with resistance values of 5, 10, and 15 Ohms. What is the total resistance of the circuit? 30 ohms A series circuit has 3 resistors, with resistance values of 5, 10, and 15 Ohms. The voltage source is 120 volts, what is the current (amps) moving through the circuit? 4 A series circuit has 3 resistors, with resistance values of 5, 10, and 15 Ohms. The voltage source is 120 volts. What is the current (amps) moving through the 10 Ohm resistor? 4 amps A series circuit has 3 resistors, with resistance values of 5, 10, and 15 Ohms. The voltage source is 120 volts and the current is 4 amps. What is the voltage drop across the 10 ohm resistor? 40 volts A series circuit has 3 resistors, with resistance values of 5, 10, and 15 Ohms. The voltage source is 120 volts and the current is 4 amps. What is the total voltage drop (volts) for all three resistors? 120 volts One of the resistors is removed from the series circuit in the previous question, so that the circuit is still closed but only two resistors remain. The voltage drop (volts) across each of the remaining two resistors will remain unchanged. False Three light bulbs are connected in parallel, to a battery which provides 15 amps of current to the circuit. If the current through the first bulb is 5 amps and the current through the second bulb is 4 amps, what is the current (amps) flowing through the third bulb? 6 amps Of the two light bulbs with 4 and 5 amps of current flowing through them, which will shine the brightest? the bulb experiencing 5 amps of current If a resistor is removed from a parallel circuit, the remaining resistors will experience the same amount of voltage drop as before. True 5 and 10 Ohm resistors are connected in parallel to a 30 volt battery. The voltage drop across the 5 Ohm resistor is __________ volts and the voltage drop across the 10 Ohm resistor is _________ volts. 30/30 15 and 60 Ohm resistors are connected in parallel to a battery which provides 10 A of current. The total resistance (Ohms) of the circuit is _____________ . 12 15 and 60 Ohm resistors are connected in parallel to a battery which provides 10 A of current. The current (amps) moving through the 15 Ohm resistor is 8 15 and 60 Ohm resistors are connected in parallel to a battery which provides 10 A of current. What is the voltage (volts) of the battery supplying the current? 120 The two resistors in the previous question were 15 and 60 Ohms. If these two resistors had been connected in a series circuit what would have been the total resistance (Ohms) of the circuit? 75 Which of the two circuit types with the 15 and 60 Ohm resistors would have had the greatest current flowing? Parallel or Series? Parallel If two circuits (a series circuit and a parallel circuit) have identical voltage sources and resistors, which circuit will generate the most current? Parallel Home electric wiring is connected in ____________ and when the wiring overheats, a fuse or breaker will make the circuit _____________ to prevent fire in the wiring. parallel/open The source of all magnetic fields is ___________ . Magnetic poles repel each other when the poles are ____________ and the Earth's north magnetic pole actually acts like a conventional magnetic's ___________ pole. moving electric charge (current) / like / south The magnetic field associated with an atom is mostly due to electron ____________ and when the atoms influence the other atoms around them in a "magnetic" material, these form a __________ of many aligned atoms with a magnetic field aligned in the same direction. Spin/domain Magnetic field lines move out from a magnetic ____________ pole and into a magnetic ____________ pole. A magnetic field ____________ be monopole (single north or south pole). north / south / cannot Which of the following metals are naturally "magnetic", i.e. naturally have a tendency to hold a magnetic field of their own? a. Iron b. nickel c. copper d. a and b e. a, b, and c a, b, and c d. a and b When an electron current flows through a coil (solenoid - see ppt lecture 24 regarding electron current flow through a solenoid) a magnetic field is generated that resembles (looks like) a bar magnet The magnetic field generated by a long, straight current carrying wire forms ____________ around the wire and the magnetic field formed will be ____________ to the original current. rings / perpendicular to Which of the following will increase the strength of a magnetic field generated by current flowing through a solenoid? a. Increase the number of loops in the wire around the solenoid b. place a material which can be magnetized, inside the solenoid c. decrease the current flow through the wire that is looped around the solenoid d. a and b e. a, b and c d. a and b There is no magnetic force on a charged particle moving parallel to a magnetic field. The force of a magnetic field is maximum on a charge which is in motion perpendicular to the magnetic field. True The ____________ is the rotating part of an electric motor and when current is passed through this part, it becomes an ______________ . armature / electromagnet When the needle of a compass in the northern hemisphere points to north, it is pointing to the geographic location of the Earth's _____________ magnetic pole and this is also the ____________ end of a natural magnetic dipole. north/south A solenoid has current flowing through it. Which of the following will increase the strength of the magnetic field which is generated by the current? a. Increase the number of wire loops around the solenoid b. increase the current through the solenoid c. add a core of iron, nickel or cobalt to the inside of the solenoid d. a and b e. a, b, and c e. a, b, and c A / an _______________ converts electrical energy to mechanical energy and a / an _____________ converts mechanical energy to electrical energy. electric motor / electric generator If I move a closed conducting loop through a magnetic field, a / an ____________ is ___________ current / generated Tesla and Westinghouse were the first to build an electric generator (Niagara Falls power plant), applying Faraday's law of induction. True Generators produce AC current and transformers use DC current in the transformer process False The primary of a transformer and not the secondary is connected to the voltage source. True In a step down transformer, the ratio of voltage to turns (V/T) decreases from the primary to the secondary. False In a transformer, power is conserved so that the power into the primary = the power coming out of the secondary. In a step down transformer, the voltage component of the power in the primary is decreased in the secondary so that there is less voltage coming out of the secondary. True According to our text (ch 25.5) a transformer "steps voltage up or down" and does this without changing the total energy. True Transformers transform ____________ Voltage The output voltage in the secondary of a transformer depends on the _____________ . number of windings (loops) on each side (on the primary side and on the secondary side) A closed loop of wire is present in a magnetic field. If a voltage is induced in the loop, the amount of voltage depends on the _______________ . rate of change of the magnetic field influencing the loop Which of the following is not one of the three primary rules / principles that govern operation of transformers? ratio of volts to windings is the same in both the primary and the secondary b. current into the primary = current out from the secondary c. power into the primary = power out from the secondary d. Power = current x voltage b. current into the primary = current out from the secondary A transformer with 35 primary coils and 105 secondary coils is connected to a 200 volt source. This is a step _________ (answer with "up" or "down", all lower case, no capitols) transformer . up A transformer with 35 primary coils and 105 secondary coils is connected to a 200 volt source. What will the output (secondary) voltage be for the transformer? 600 A transformer with 125 primary coils and 25 secondary coils is connected to a 50 volt battery which provides 5 amps of current. The current through the secondary is ______________ amps and the power out of the secondary is ______________ . 25/250 A transformer with 90 primary coils and 15 secondary coils is connected to a 60 V voltage source with an initial power of 30 watts. What is the voltage output in the secondary? 10 A transformer with 90 primary coils and 15 secondary coils is connected to a 60 V voltage source with an initial power of 30 watts. What is the output current? 3 amps A transformer with 90 primary coils and 15 secondary coils is connected to a 60 V voltage source with an initial power of 30 watts. What is the output power? 30 watts