Q&A Hero

Q: Some of the factors that engineers consider when selecting a motor for an application are: a. motor type and speed (rpm). b. motor performance and efficiency. c. cost, life expectancy, and noise level. d. maintenance and service requirements. e. all of the above

Q: How many kW-hour is consumed by a TV set that uses 250 watts when it is left on for 4 hours? a. 250 b. 1000 c. 1 d. 0.25

Q: One kilowatt hour represents the amount of power consumed during 1 hour by a device that uses one kilowatt (kW). a. True b. False

Q: Capacitors are used for a. energy storage b. electronic filters c. timing elements d. all of the above

Q: Electrical components that store energy on two oppositely charged electrodes, rather than through a chemical reaction are known as a. batteries b. inductors c. transistors d. capacitors

Q: In certain circuits, if one of the elements fails, that failure prevents the current from flowing through other elements in the circuit; thus the entire circuit fails. This type of circuit is a a. parallel circuit b. series circuit c. none of the above

Q: Electrical resistance is a fundamental dimension. a. True b. False

Q: When it comes to wire size, the larger the gage number the larger the wire diameter. a. True b. False

Q: The ratio of the diameter of No. 1 AWG wire to No. 2 is a. 1.25 b. 1.5 c. 2.0 d. 1.12

Q: A numbering system that describes the size of an electric conductor is AWG. What does AWG stand for? a. American Wire Gage b. Association of Wire Gages c. Atlas of Wire Gages d. All Wire Gages

Q: Ohm's law describes the relationship between voltage, resistance, and current. Which of these is Ohm's law? a. b. c. d.

Q: Some materials exhibit near-zero resistance at very low temperatures. This behavior is called a. infra-resistance b. anti-resistance c. semiconductivity d. superconductivity

Q: The electrical resistance of a material does not vary with temperature. a. True b. False

Q: An electrical circuit refers to the combination of various electrical components that are connected together. a. True b. False

Q: The law that states that at any given time, the sum of the currents entering a node must equal the sum of the currents leaving the node is know as a. Kirchoff's current law b. Kirchoff's voltage law c. Ohm's law d. Coulomb's law

Q: The flow of electric charge that periodically reverses direction that is typically produced by rotating generators is known as a. ac current. b. dc current. c. ac/dc current. d. omni directional current.

Q: The flow of electric charge that occurs in one direction that is typically produced by batteries is known as a. ac current. b. dc current. c. ac/dc current. d. unidirectional current.

Q: In general, there are two ways in which the sun's energy is converted into electricity: a. photovoltaic and photothermal b. photovoltaic and photochemical c. photovoltaic and photosynthetic d. none of the above

Q: Which of the following batteries is an example of a primary cell? a. Nickel-cadmium (NiCd) also known as "nicad" b. Nickel-metal hydride (NiMH) c. Alkaline d. Lead acid

Q: Primary cells are batteries that can be recharged while secondary cells are batteries that cannot be recharged. a. True b. False

Q: In all batteries, electricity is produced by a. light b. heat c. a chemical reaction d. all of the above

Q: Voltage is sometime referred to as emf. What does emf stand for? a. Electromagnetic frequency b. Electromotive frequency c. Electromagnetic force d. Electromotive force

Q: The amount of work required to move charge between two points is represented by a. electric current b. resistance c. voltage d. energy

Q: One coulomb is defined as the amount of charge that passes a point in a wire in 1 second when a current of 1 ampere is flowing through the wire. a. True b. False

Q: The flow of charge will occur when the two bodies are connected by an electrical conductor such as a copper wire. The flow of electric charge is called electric current. a. True b. False

Q: The SI unit for electric current is a. amperes b. electrons per second c. coulombs d. watts

Q: In SI units, the unit of charge is the coulomb (C). a. True b. False

Q: The basic law of electric charges states that unlike charges attract each other while like charges repel. a. True b. False

Q: Which subatomic particle has no charge? a. Proton b. Neutron c. Electron d. Ion

Q: Which subatomic particle has a positive charge? a. Proton b. Neutron c. Electron d. Ion

Q: Which subatomic particle has a negative charge? a. Proton b. Neutron c. Electron d. Ion

Q: Electric current is a fundamental dimension. a. True b. False

Q: Every engineer needs to understand the fundamentals of electricity and magnetism. a. True b. False

Q: A degree-day (DD) is the difference between 65F (typically) and the average temperature of the outside air during a 24-hour period. a. True b. False

Q: The energy released by fuel when the combustion by-products include water in vapor form is known as the a. higher heating value b. lower heating value c. all of the above d. none of the above

Q: The energy released by fuel when the combustion by-products include water in liquid form is known as the a. higher heating value b. lower heating value c. all of the above d. none of the above

Q: The term that is used to quantify the amount of energy that is released when a unit mass or a unit volume of fuel is burned is known as a. heating value b. specific heat c. specific mass d. specific volume

Q: Most conventional fuels that we use today to generate power come from coal, natural gas, oil, or gasoline. a. True b. False

Q: How much energy is required to raise the temperature of of aluminum from to ?

Q: You wish to make a large cup of tea. How much energy is needed to raise the temperature of 500 ml of tap water from to ?

Q: A steel bridge is 150 m long when the temperature is . By how much will its length increase when the temperature is ? (Steel has a coefficient of linear expansion of

Q: The physical quantity that provides a quantitative way to show how much thermal energy is required to raise the temperature of an object by a certain amount is a. thermal conductivity b. specific heat c. specific weight d. density

Q: In general, as the temperature of a material is increased, the material's volume will a. increase b. decrease c. remain the same

Q: In general, as the temperature of a material is increased, the material's length will a. increase b. decrease c. remain the same

Q: A unit that is generally used to express the insulating value of clothing is called a. clo b. ciu c. cins d. ivc

Q: A unit commonly used to express the metabolic rate for an average person under sedentary conditions is called a. metabavg b. mravg c. met d. msed

Q: The physical measurement that is intended to account for the combined effect of wind speed and air temperature is known as a. Dew point b. Ambient conditions c. Wind chill index b. Relative temperature

Q: If you stay out too long at the beach you may get a sunburn as a result of too much heat being transferred to your skin. What mode of heat transfer is responsible for this? a. conduction b. convection c. radiation d. none of the above

Q: Before taking a bite of a piece of hot pizza you blow on it to cool it What mode of heat transfer are you using in this situation? a. conduction b. convection c. radiation d. none of the above

Q: When you touch a hot object with your finger, the heat transferred to your finger is by a. conduction b. convection c. radiation d. none of the above

Q: All matter emits thermal radiation. This rule is true as long as the body in question is at a nonzero absolute temperature. a. True b. False

Q: For both the forced and the free convection situations, the overall heat transfer rate between the fluid and the surface is governed by Fourier's law of cooling. a. True b. False

Q: The mode of heat transfer that occurs when a fluid in motion comes into contact with a solid surface whose temperature differs from the moving fluid is known as a. conduction b. convection c. radiation d. none of the above

Q: The R-value or R-factor of a material provides a measure of resistance to heat flow: The higher the value, the less resistance to heat flow the material offers. a. True b. False

Q: Thermal conductivity is a property of materials that shows how good the material is in transferring thermal energy (heat) from a high-temperature region to a low-temperature region within the material. a. True b. False

Q: The mode of heat transfer that occurs when a temperature difference exists in a medium is known as a. conduction b. convection c. radiation d. none of the above

Q: What is the SI unit of thermal energy? a. Calorie b. Watt c. Btu d. Joule

Q: The energy content of food is typically expressed in Calories, which is equal to 1000 calories. a. True b. False

Q: The amount of heat required to raise the temperature of of water by is known as a a. Btu b. calorie c. Calorie d. Joule

Q: The amount of heat required to raise the temperature of 1 lbm of water by is known as a a. Btu b. calorie c. Calorie d. Joule

Q: What does Btu stand for? a. British temperature unit b. British thermal unit c. British thermocouple unit d. Binary temperature unit

Q: Heat flows naturally from a hot object to a cold objects. a. True b. False

Q: Which of the following is NOT a mode of heat transfer? a. transposition b. convection c. radiation d. conduction

Q: A temperature difference in Celsius is equal to a temperature difference in Kelvin. a. True b. False

Q: A temperature difference in Celsius is equal to a temperature difference in Fahrenheit. a. True b. False

Q: The temperature in this room is . The temperature outside the building is . What is the temperature difference in degrees Celsius? a. b. c. d.

Q: The temperature in a room is . The temperature outside the building is . What is the temperature difference in Kelvins? a. 52 K b. 11 K c. 20 K d. 29 K

Q: When using the ideal gas law, , what system of units should you use when entering temperature values? a. Fahrenheit b. Celsius c. Kelvin d. any of the above

Q: What does T stand for in the following equation (ideal gas law)? a. Time b. Period c. Torque d. Temperature

Q: What does V stand for in the following equation (ideal gas law)? a. Volume b. Velocity c. Voltage d. Viscosity

Q: What does P stand for in the following equation (ideal gas law)? a. Pounds b. Pressure c. Power d. Permeability

Q: The Kelvin and Rankine scales are based on the behavior of an ideal gas. a. True b. False

Q: Which of the following temperature scales is known as an absolute scale? a. Rankine b. Kelvin c. all of the above

Q: Which of the following temperature scales is known as an absolute scale? a. Fahrenheit b. Celsius c. Centigrade d. Kelvin

Q: Convert to Kelvins

Q: Convert to Kelvins

Q: Convert to Fahrenheit

Q: Convert to Celsius

Q: A temperature-measuring device composed of a semiconductor material is known as a a. Thermocouple b. Thermistor c. Thermojunction d. RTD

Q: A temperature-measuring device that consists of two dissimilar metals is known as a a. Thermocouple b. Thermistor c. Thermojunction d. RTD