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Drupady [299]
3 years ago
10

Analyze: To gauge the efficiency of a light bulb, it is also important to consider how much light it produces. Light intensity i

s measured in lumens (lm). A lumen is equal to the light produced by a single candle. The lumens produced by each type of light are listed below. To compare the efficiency of each bulb, calculate how many lumens each bulb produces per watt. To do this, divide the number of lumens by the wattage for each lamp. Include all units. Lamp Lumens (lm) Wattage (W) Lumens per watt (lm/W) Incandescent 800 lm 60W 13.3 Im/W Halogen 6,000 lm 300W 20 Im/W Fluorescent 2,000 lm 30W 66.7 Im/W A. Which lamp produces light most efficiently
Physics
1 answer:
otez555 [7]3 years ago
4 0

Answer:

The Fluorescent lamp is most efficient

Explanation:

66.7 lumens/watt

Fluorescent was always the most efficient vs. incandescent or halogen gas envelope

This question needs some updating as LED lamps now beat fluorescents in life expectancy and lumens/watt.

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April and Alex are saving money to buy new phones. Each friend starts with some money and saves a specific amount each week.
qwelly [4]
First thing to note is that we are on week 0, when they start saving:

The equation for Alex is:

y=20x + 125 

Know that we are on week 0, and x is our weeks, that makes our equation:

y=20(0) + 125 

Which means it's really:

y=125

That means that the first one is E. 125

For the second, it shows our week 0, which is at 100.

That means that the second one is I. 100

Hope this helps!
5 0
4 years ago
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An object will sink in a liquid if the density of the object is greater than that of the liquid. The mass of a sphere is 9.83 g.
Talja [164]

I don't know

I need more information

5 0
3 years ago
What change in entropy occurs when a 0.15 kg ice cube at -18 °C is transformed into steam at 120 °c 4.
Studentka2010 [4]

<u>Answer:</u> The change in entropy of the given process is 1324.8 J/K

<u>Explanation:</u>

The processes involved in the given problem are:

1.)H_2O(s)(-18^oC,255K)\rightarrow H_2O(s)(0^oC,273K)\\2.)H_2O(s)(0^oC,273K)\rightarrow H_2O(l)(0^oC,273K)\\3.)H_2O(l)(0^oC,273K)\rightarrow H_2O(l)(100^oC,373K)\\4.)H_2O(l)(100^oC,373K)\rightarrow H_2O(g)(100^oC,373K)\\5.)H_2O(g)(100^oC,373K)\rightarrow H_2O(g)(120^oC,393K)

Pressure is taken as constant.

To calculate the entropy change for same phase at different temperature, we use the equation:

\Delta S=m\times C_{p,m}\times \ln (\frac{T_2}{T_1})      .......(1)

where,

\Delta S = Entropy change

C_{p,m} = specific heat capacity of medium

m = mass of ice = 0.15 kg = 150 g    (Conversion factor: 1 kg = 1000 g)

T_2 = final temperature

T_1 = initial temperature

To calculate the entropy change for different phase at same temperature, we use the equation:

\Delta S=m\times \frac{\Delta H_{f,v}}{T}      .......(2)

where,

\Delta S = Entropy change

m = mass of ice

\Delta H_{f,v} = enthalpy of fusion of vaporization

T = temperature of the system

Calculating the entropy change for each process:

  • <u>For process 1:</u>

We are given:

m=150g\\C_{p,s}=2.06J/gK\\T_1=255K\\T_2=273K

Putting values in equation 1, we get:

\Delta S_1=150g\times 2.06J/g.K\times \ln(\frac{273K}{255K})\\\\\Delta S_1=21.1J/K

  • <u>For process 2:</u>

We are given:

m=150g\\\Delta H_{fusion}=334.16J/g\\T=273K

Putting values in equation 2, we get:

\Delta S_2=\frac{150g\times 334.16J/g}{273K}\\\\\Delta S_2=183.6J/K

  • <u>For process 3:</u>

We are given:

m=150g\\C_{p,l}=4.184J/gK\\T_1=273K\\T_2=373K

Putting values in equation 1, we get:

\Delta S_3=150g\times 4.184J/g.K\times \ln(\frac{373K}{273K})\\\\\Delta S_3=195.9J/K

  • <u>For process 4:</u>

We are given:

m=150g\\\Delta H_{vaporization}=2259J/g\\T=373K

Putting values in equation 2, we get:

\Delta S_2=\frac{150g\times 2259J/g}{373K}\\\\\Delta S_2=908.4J/K

  • <u>For process 5:</u>

We are given:

m=150g\\C_{p,g}=2.02J/gK\\T_1=373K\\T_2=393K

Putting values in equation 1, we get:

\Delta S_5=150g\times 2.02J/g.K\times \ln(\frac{393K}{373K})\\\\\Delta S_5=15.8J/K

Total entropy change for the process = \Delta S_1+\Delta S_2+\Delta S_3+\Delta S_4+\Delta S_5

Total entropy change for the process = [21.1+183.6+195.9+908.4+15.8]J/K=1324.8J/K

Hence, the change in entropy of the given process is 1324.8 J/K

4 0
3 years ago
What is mercury barometer​
Allisa [31]
A mercury barometer is a device that is used to measure atmospheric pressure at a location. :)
3 0
3 years ago
A motorcycle moving 18.8 m/s has<br> 57800 J of KE. What is its mass?<br> (Unit = kg)
Nady [450]

Answer:10

Explanation:

3 0
3 years ago
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