EGEE 101- Exam 1 2025 Questions and
Answers
Radiaton - ....ANSWER ...-Radiative heat transfer is how the "warmth" of the sun
is transferred to you when you're out or how you warm your hands in front of the fire.
Convective - ....ANSWER ...-Convection is the heat transfer due to bulk movement
of molecules within fluids. -The water molecules are free to roam about as they are not
fixed in relative positions (unless frozen) like the metal atoms. So as a water molecule
heats up, it has more energy and travels further. The molecules moving around have lots
of collisions (think bumper cars), but this "molecular billiards" occurs without energy
loss, and so, imagine breaking at pool but the balls never stop; they will keep on
colliding until there is a distribution of energy. This distribution will be a certain shape
with a certain portion of the molecules having certain energy levels. As the water warms
up, this distribution will simply shift to the right into a higher energy level (temperature).
The Refrigerator : - ....ANSWER ...-The casing is simply an insulated box, so the
heat cannot get in (remember that heat flows from hot to cold, so it would not be correct
to say insulation keeps the cold in). At the back, there is a heat exchanger, a coil where
the heat from inside the refrigerator can be dissipated—yes, this means that in the
summer your refrigerator is pumping out heat which you are removing with the air
conditioner (silly, isn't it!) But as heat flows from hot to cold, how did we manage to get
it to flow the other way? We used a heat pump, to which we give energy so we can move
heat; this is achieved because of the properties of the refrigerant and the use of the
…FOR STUDENTS ONLY…©️2025 ALL RIGHTS RESERVED… 1
,compressor (the noise that comes intermittently from the refrigerator is the compressor,
or, perhaps the ice maker). The refrigerant will be a liquid with a low boiling point.
Thus, we can easily convert refrigerant from the liquid phase into the gas phase.
INCANDESCENT - ....ANSWER ...-Light bulbs need electricity, which is used to
heat a tungsten filament. The thin metal strand (the filament) gets so hot it becomes
white-hot, producing a nice white light. The bulb itself is simply an envelope in which
we can put inert gases so the filament does not burn.
- gives off too much heat
Efficiency Measure - ....ANSWER ...-Efficiency Measure
FLUORESCENT - ....ANSWER ...-Much of the energy required to "light" a
fluorescent light is needed as soon as the light switch is turned on. The electrodes at
either end of the lamp are the starting point for the electron to "flow" through the tube
(from one electrode to the other). As they pass through the tube they excite the mercury
vapor inside the tube; the excited mercury gives off ultraviolet radiation.
-The lower rate of energy use (wattage) will however still produce as much light as an
incandescent light because of the efficiency increase over the incandescent lighting (look
at lumens levels to compare)
LIGHT EMITTING DIODE (LED) - ....ANSWER ...--LED's are small light
sources that become illuminated by the movement of electrons through a semiconductor
material
(link is external)
-Recently, they have become a lighting option for white light (often directional lighting
for task lighting: reading lamps, counter tops, etc.)
…FOR STUDENTS ONLY…©️2025 ALL RIGHTS RESERVED… 2
, -they are increasingly common in general lighting and have a nicer color than compact
fluorescent lighting
-used in traffic lights, streetlights, xmas tree lights, etc.
-They use less electricity, the light is closer to incandescent in color, and they last longer.
HALOGEN LIGHTS - ....ANSWER ...-These are great lights for producing lots of
heat and very bright light.
-Halogen lights do have their uses, however - exterior security lighting, sporting event
lighting, headlights in your car (for those driving the nicer cars anyway).
COMPACT FLUORESCENT LIGHTING - ....ANSWER ...-- 3 types
-The incandescent light bulb produces light by heating a tungsten wire to white hot
temperatures.
-The advantage is that your electricity bill will be less because for the same production of
light (how many lumens), less electricity is used.
-The advantage is that your electricity bill will be less because for the same production of
light (how many lumens), less electricity is used.
- more expensive to purchase but compact fluorescent bulbs make a great deal of
economic and environmental sense (electricity comes mostly from aging fossil fuel
utilities that produce air pollution).
-not much heat
R values - ....ANSWER ...-We use R values to measure the insulating property of
the material (the resistance of an area of material to heat flow over time). The units are:
…FOR STUDENTS ONLY…©️2025 ALL RIGHTS RESERVED… 3
Answers
Radiaton - ....ANSWER ...-Radiative heat transfer is how the "warmth" of the sun
is transferred to you when you're out or how you warm your hands in front of the fire.
Convective - ....ANSWER ...-Convection is the heat transfer due to bulk movement
of molecules within fluids. -The water molecules are free to roam about as they are not
fixed in relative positions (unless frozen) like the metal atoms. So as a water molecule
heats up, it has more energy and travels further. The molecules moving around have lots
of collisions (think bumper cars), but this "molecular billiards" occurs without energy
loss, and so, imagine breaking at pool but the balls never stop; they will keep on
colliding until there is a distribution of energy. This distribution will be a certain shape
with a certain portion of the molecules having certain energy levels. As the water warms
up, this distribution will simply shift to the right into a higher energy level (temperature).
The Refrigerator : - ....ANSWER ...-The casing is simply an insulated box, so the
heat cannot get in (remember that heat flows from hot to cold, so it would not be correct
to say insulation keeps the cold in). At the back, there is a heat exchanger, a coil where
the heat from inside the refrigerator can be dissipated—yes, this means that in the
summer your refrigerator is pumping out heat which you are removing with the air
conditioner (silly, isn't it!) But as heat flows from hot to cold, how did we manage to get
it to flow the other way? We used a heat pump, to which we give energy so we can move
heat; this is achieved because of the properties of the refrigerant and the use of the
…FOR STUDENTS ONLY…©️2025 ALL RIGHTS RESERVED… 1
,compressor (the noise that comes intermittently from the refrigerator is the compressor,
or, perhaps the ice maker). The refrigerant will be a liquid with a low boiling point.
Thus, we can easily convert refrigerant from the liquid phase into the gas phase.
INCANDESCENT - ....ANSWER ...-Light bulbs need electricity, which is used to
heat a tungsten filament. The thin metal strand (the filament) gets so hot it becomes
white-hot, producing a nice white light. The bulb itself is simply an envelope in which
we can put inert gases so the filament does not burn.
- gives off too much heat
Efficiency Measure - ....ANSWER ...-Efficiency Measure
FLUORESCENT - ....ANSWER ...-Much of the energy required to "light" a
fluorescent light is needed as soon as the light switch is turned on. The electrodes at
either end of the lamp are the starting point for the electron to "flow" through the tube
(from one electrode to the other). As they pass through the tube they excite the mercury
vapor inside the tube; the excited mercury gives off ultraviolet radiation.
-The lower rate of energy use (wattage) will however still produce as much light as an
incandescent light because of the efficiency increase over the incandescent lighting (look
at lumens levels to compare)
LIGHT EMITTING DIODE (LED) - ....ANSWER ...--LED's are small light
sources that become illuminated by the movement of electrons through a semiconductor
material
(link is external)
-Recently, they have become a lighting option for white light (often directional lighting
for task lighting: reading lamps, counter tops, etc.)
…FOR STUDENTS ONLY…©️2025 ALL RIGHTS RESERVED… 2
, -they are increasingly common in general lighting and have a nicer color than compact
fluorescent lighting
-used in traffic lights, streetlights, xmas tree lights, etc.
-They use less electricity, the light is closer to incandescent in color, and they last longer.
HALOGEN LIGHTS - ....ANSWER ...-These are great lights for producing lots of
heat and very bright light.
-Halogen lights do have their uses, however - exterior security lighting, sporting event
lighting, headlights in your car (for those driving the nicer cars anyway).
COMPACT FLUORESCENT LIGHTING - ....ANSWER ...-- 3 types
-The incandescent light bulb produces light by heating a tungsten wire to white hot
temperatures.
-The advantage is that your electricity bill will be less because for the same production of
light (how many lumens), less electricity is used.
-The advantage is that your electricity bill will be less because for the same production of
light (how many lumens), less electricity is used.
- more expensive to purchase but compact fluorescent bulbs make a great deal of
economic and environmental sense (electricity comes mostly from aging fossil fuel
utilities that produce air pollution).
-not much heat
R values - ....ANSWER ...-We use R values to measure the insulating property of
the material (the resistance of an area of material to heat flow over time). The units are:
…FOR STUDENTS ONLY…©️2025 ALL RIGHTS RESERVED… 3
