Physical Science Electricity and Electronics/ heat
1. A silver bar 0.125...
1. A silver bar 0.125 meter long is subjected to a temperature change from 200Â°C to 100Â°C. What will be the length of the bar after the temperature change?
Submitted: 15 years ago.Category: Homework
A. 0.124764 meter
B. 0.00023635 meter
C. 0.00002363 meter
D. 0.0000189 meter
2. When the molecules in a body move with increased speed, it's possible that the body will change from a
A. gas to a liquid.
B. gas to a solid.
C. liquid to a solid.
D. liquid to a gas.
3. If the absolute temperature of a gas is 600 K, the temperature in degrees Celsius is
4. The main purpose of the turbine in the turbojet engine is to
A. drive the compressor.
B. compress the air.
C. increase the velocity of the exhaust gases.
D. reduce the temperature of the exhaust gas.
5. 20 cubic inches of a gas with an absolute pressure of 5 psi is compressed until its pressure reaches 10 psi. What is the new volume of the gas? (Assume that there's no change in temperature.)
A. 5 cubic inches
B. 10 cubic inches
C. 40 cubic inches
D. 100 cubic inches
6. Unlike other kinds of liquids, volatile liquids
A. ignite readily at a relatively low temperature.
B. flow rapidly at a relatively low temperature.
C. evaporate rapidly at a relatively low temperature.
D. freeze readily at a relatively high temperature.
7. A temperature of 273 K is the temperature at which water
B. lacks any moving molecules.
8. Which of the following takes place in the combustion chamber of a gas turbine engine?
A. Fuel oil is stored with sufficient pressure.
B. Fuel oil is mixed with a proper portion of compressed air.
C. A mixture of fuel oil and compressed air is ignited.
D. Gases are cooled to a desired temperature.
9. How much heat energy is required to raise the temperature of 5 kilograms of coal from 20Â°C to 220Â°C?
A. 314 J
B. 6,573 J
C. 1,314,718 J
D. 4,187,000 J
10. One degree Celsius indicates the same temperature change as
A. one degree Fahrenheit.
B. one kelvin.
C. 5/9 degree Fahrenheit.
D. 9/5 kelvin.
11. A quantity of a gas has an absolute pressure of 400 kPa and an absolute temperature of 110 degrees kelvin. When the temperature of the gas is raised to 235 degrees kelvin, what is the new pressure of the gas? (Assume that there's no change in volume.)
A. 1.702 kPa
B. 3.636 kPa
C. 510 kPa
D. 854.46 kPa
12. A temperature of 20Â°C is equivalent to approximately
13. If the absolute pressure of a gas is 550.280 kPa, its gage pressure is
A. 101.325 kPa.
B. 277.280 kPa.
C. 448.955 kPa.
D. 651.605 kPa.
14. Which one of the following substances is a liquid fuel used in rocket engines?
A. Liquid oxygen
C. Potassium perchlorate
D. Codium nitrate
15. The density of water is the greatest at a temperature of
A. 0 K.
B. 4 K.
C. 273 K.
D. 277 K.
16. In a gasoline engine, the area in the cylinder head where the air-and-fuel mixture is burned is called the
C. combustion chamber.
D. intake valve.
17. How much heat is required to convert 0.3 kilogram of ice at 0Â°C to water at the same temperature?
A. 100,375 J
B. 167,292 J
C. 334,584 J
D. 450,759 J
18. Which of the following cools the air in a household refrigerator?
A. Reduction of the air temperature due to condensation of the gaseous refrigerant
B. The transfer of heat from the air to the compressor due to expansion of the gaseous refrigerant
C. The transfer of heat to the evaporator due to compression of the liquid refrigerant
D. Absorption of the heat from the air due to evaporation of the liquid refrigerant
19. Which one of the following temperatures is equal to 5Â°C?
A. 0 K
B. 41 K
C. 278 K
D. 465 K
20. Liquid alcohol will change to vapor when its temperature reaches the
A. boiling point.
B. fusing point.
C. freezing point.
D. melting point.
21. A temperature of 200Â°F is equivalent to approximately
22. A quantity of gas has a volume of 0.20 cubic meter and an absolute temperature of 333 degrees kelvin. When the temperature of the gas is raised to 533 degrees kelvin, what is the new volume of the gas? (Assume that there's no change in pressure.)
A. 0.0006 m3
B. 0.2146 m3
C. 0.2333 m3
D. 0.3198 m3
23. Which of the following statements correctly describes the position of the intake and exhaust valves during most of the power stage in a four-cycle gas engine?
A. The intake valve is closed and the exhaust valve is open.
B. The intake valve is open and the exhaust valve is closed.
C. Both the intake valve and the exhaust valve are closed.
D. Both the intake valve and the exhaust valve are open.
24. What is the length of an aluminum rod at 65Â°C if its length at 15Â°C is 1.2 meters?
A. 0.001386 meter
B. 0.00180 meter
C. 1.201386 meters
D. 1.214855 meters
25. Heat from burning fuel warms the walls of the firebox section of the furnace in
A. a hot-air heating system.
B. an evaporation system.
C. a compressor compartment.
D. a hot-water heating system.
1. If one body is positively charged and another body is negatively charged, free electrons tend to
A. move from the negatively charged body to the positively charged body.
B. move from the positively charged body to the negatively charged body.
C. remain in the negatively charged body.
D. remain in the positively charged body.
2. A battery consists of five dry cells connected in series. If the voltage developed by each cell is 1.5 V, the total voltage developed by the battery is
A. 0.3 V.
B. 1.5 V.
C. 5.0 V.
D. 7.5 V.
3. The grid in a high-vacuum triode is usually kept negatively charged with respect to the cathode so that the electrons may be
A. accelerated toward the anode.
B. accelerated toward the cathode.
C. attracted to the anode instead of the grid.
D. attracted to the cathode instead of the grid.
4. An example of an atom that has no charge is one that has
A. 2 protons, 2 electrons, and 1 neutron.
B. 1 proton, 2 electrons, and 3 neutrons.
C. 3 protons, 1 electron, and 3 neutrons.
D. 3 protons, 2 electrons, and 1 neutron.
5. If an electrically uncharged body is contacted by an electrically charged body, the uncharged body will
A. develop the opposite charge as the charged body.
B. remain a neutrally charged body.
C. develop the same charge as the charged body.
D. neutralize the charged body.
6. What bias conditions must be present for the normal operation of a transistor amplifier?
A. The emitter-base junction must be reverse biased, and the collector-base junction must be forward biased.
B. The emitter-base junction must be forward biased, and the collector-base junction must be reverse biased.
C. Both junctions must be reverse biased.
D. Both junctions must be forward biased.
7. When an electric current flows through a long conductor, each free electron moves
A. from one end of the conductor to the other end.
B. with a speed of 300,000,000 m/s.
C. back and forth between the ends of the conductor.
D. through a relatively short distance.
8. If the resistance of an electric circuit is 12 ohms and the voltage in the circuit is 60 V, the current flowing through the circuit is
A. 0.2 A.
B. 5 A.
C. 60 A.
D. 720 A.
9. Electrons are emitted from a conductor when the conductor is
A. exposed to weak light.
B. cooled rapidly.
C. bombarded by high-speed electrons.
D. subjected to a small voltage.
10. A circuit contains two devices that are connected in parallel. If the resistance of one of these devices is 12 ohms and the resistance of the other device is 4 ohms, the total resistance of the two devices is
A. 0.0625 ohms.
B. 0.333 ohms.
C. 3 ohms.
D. 16 ohms.
11. When a PNP transistor is connected in a circuit in the manner shown in Figure 52 of Electricity and Electronics, it can be used as a power amplifier because
A. the output current will be much smaller than the input current.
B. the output current will be much larger than the input current.
C. the output voltage will be much smaller than the input voltage.
D. the output voltage will be much larger than the input voltage.
12. The function of a capacitor in an electric circuit is to
A. allow current flow between its plates.
B. measure the amount of current in the circuit.
C. increase circuit power.
D. store electric charges.
13. In a cathode ray tube, the number of electrons that reach the fluorescent screen is controlled by the
C. deflecting plate.
14. Which of the following frequencies falls in the range of RF waves used by commercial radio broadcasting stations?
A. 60 Hz
B. 6,000 Hz
C. 600,000 Hz
D. 6,000,000 Hz
15. To use your left hand to determine the direction of the voltage developed in a moving conductor in a stationary magnetic field, you must point your
A. thumb in the direction of the magnetic flux.
B. thumb in the direction of the electromagnetic force.
C. forefinger in the direction of the lines of force.
D. forefinger in the direction of the motion.
16. A complete circuit contains two parallel-connected devices and a generator for providing the electromotive force. The resistance of the first device is 12 ohms, the resistance of the second device is 4 ohms, and the voltage developed by the generator is 40 V. What is the magnitude of the current flowing through the first device?
A. 3.33 A
B. 8 A
C. 10 A
D. 13.32 A
17. A transformer has a primary voltage of 115 V and a secondary voltage of 24 V. If the number of turns in the primary is 345, how many turns are in the secondary?
18. Look at the circuit shown in Figure A-1. If you want to stop the current flow through Device 3 in the circuit, which one of the following single switches should you open?
A. Switch S2
B. Switch S3
C. Switch S4
D. Switch S5
19. An electric heating element is connected to a 110 V circuit and a current of 3.2 A is flowing through the element. How much energy is used up during a period of 5 hours by the element?
A. 352 Wh
B. 550 Wh
C. 1,760 Wh
D. 2,580 Wh
20. The magnitude of the voltage induced in a conductor moving through a stationary magnetic field depends on the _______ and the _______ of the conductor.
A. length, speed
B. distance, circumference
C. resistance, current
D. color, capacitance
21. If a bar of copper is brought near a magnet, the copper bar will be
A. attracted by the magnet.
B. unaffected by the magnet.
C. repelled by the magnet.
D. made into an induced magnet.
22. When all parts of a circuit are composed of conducting materials, the circuit is said to be
23. When an electron is displaced in a semiconductor, the hole that's left behind is
A. attracted to the negative terminal of the voltage source.
B. incapable of carrying a charge.
C. attracted to the anode of the voltage source.
D. considered an impurity in the crystal.
24. Including a full-wave rectifier in an AC circuit will yield a(n) _______ current.
A. intermittent direct
B. intermittent alternating
C. continuous direct
D. continuous alternating
25. Suppose that you're facing a straight current-carrying conductor, and the current is flowing toward you. The lines of magnetic force at any point in the magnetic field will act in
A. the same direction as the current.
B. a clockwise direction.
C. the direction opposite to the current.
D. a counterclockwise direction.