Q4) Ali is trying to make his mind between two different types of light bulbs to be installed in his new villa based on their efficacy, and how much it would cost to run each light. Option 1 is a standard CFL light that consumes 95 watts and has an illumination rating of 1800 lumens and costs $0.55 and has a service life of 650 hours. Option 2 is LED light that consumes 35 watts and has an illumination rating of 2300 lumens and costs $1.85 and has a service life of 900 hours. Calculate efficacy and how much it would cost to run each light for 13 hours per day for 60 days as the electric company charges 15 cents per kWh and state which option should Ali go with? (1 kW = 1000 W) Light Produced (lumens) Energy Consumed by the Lamp (watts) Efficacy =
Latent heat and phase change
A physical process in which a conversion among the basic states or phases of matter, i.e., solid, liquid, and gas takes place under the effect of a certain temperature and pressure is referred to as a phase change. Generally, the phase change of a substance occurs when heat transfer takes place between the substance and its surroundings. Based on the direction in which heat transfer takes place, different types of phase changes can occur.
Triple Point of Water
The branch of physics in which observer deals with temperature related properties is called thermodynamics.
Boiling Point of Water
Everyday examples of boiling is, boiling milk, heating water. One would have observed that when we heat water it goes through various stages and at one point bubbles show in water, and water keeps splashing with bubbles bursting, we in layman terms say that water is boiling.
Freezing Point of Water
In general, the freezing point of water is 0° Celsius, or 32° Fahrenheit. This is the temperature at which water will ordinarily change from its liquid state to its solid state (ice). However, there are certain conditions that can affect the freezing point of water. For example, a liquid may be supercooled or contain impurities so that it does not freeze at the ordinary freezing point.
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