You buy a 75-W lightbulb in Europe, where electricity is delivered to homes at 240V. If you use the lightbulb in the United Stat
1 answer:
Answer:
The bulb will be times as bright as it is in Europe.
Explanation:
Data provided in the question:
Power of bulb in Europe = 75 W
Voltage provided in Europe = 240 V
Voltage provided in United Stated = 120 V
Now,
We know,
Power = Voltage² ÷ Resistance
Therefore,
75 = 240² ÷ Resistance
or
Resistance = 240² ÷ 75
or
Resistance = 768 Ω
Therefore,
Power in United States = Voltage² ÷ Resistance
= 120² ÷ 768
= 18.75 W
Therefore,
Ratio of powers
=
Hence,
The bulb will be times as bright as it is in Europe.
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Answer:
Amount of air left in the cylinder=m=0.357 Kg
The amount of heat transfer=Q=0
Explanation:
Given
Initial pressure=P1=300 KPa
Initial volume=V1=0.2
Initial temperature=T=20 C
Final Volume==0.1
Using gas equation
m1==(300*0.2)/(.287*293)
m1=0.714 Kg
Similarly
m2=(P2*V2)/R*T2
m2=(300*0.1)/(0.287*293)
m2=0.357 Kg
Now calculate mass of air left,where me is the mass of air left.
me=m2-m1
me=0.715-0.357
mass of air left=me=0.357 Kg
To find heat transfer we need to apply energy balance equation.
Where me=m1-m2
And as the temperature remains constant,hence the enthalpy also remains constant.
h1=h2=he=h
Q=(me-(m1-m2))*h
me=m1-me
Thus heat transfer=Q=0
Answer:
The exit temperature is 293.74 K.
Explanation:
Given that
At inlet condition(1)
P =80 KPa
V=150 m/s
T=10 C
Exit area is 5 times the inlet area
Now
If consider that density of air is not changing from inlet to exit then by using continuity equation
So
m/s
Now from first law for open system
Here Q=0 and w=0
When air is treating as ideal gas
Noe by putting the values
So the exit temperature is 293.74 K.