Question 1

Step 2: Convert the source value into Joules.

Accepted Answer

Formula: Source Value × Joules per Source Unit = Total Joules
Calculation: 75 kWh × 3,600,000 J/kWh = 270,000,000 Joules
You now know that 75 kWh contains exactly 270 million Joules of energy.

Question 2

Step 3: Convert the total Joules into the target unit (BTUs).

Accepted Answer

Formula: Total Joules / Joules per Target Unit = Target Value
Calculation: 270,000,000 Joules / 1,055.06 J/BTU = 255,909.6 BTUs

Question 3

What is the difference between Power and Energy?

Accepted Answer

Energy is the total amount of work done or heat generated, while Power is the rate at which that energy is used or produced over time. Think of driving a car: the total distance you travel is the Energy, while your speed in miles per hour is the Power. In electrical terms, the Kilowatt-hour (kWh) is the total energy consumed, whereas the Kilowatt (kW) is the power being drawn at any exact given second.

Question 4

Why is my natural gas bill measured in Therms instead of volume?

Accepted Answer

Natural gas utility companies measure the physical volume of gas (in hundreds of cubic feet, or CCF) that flows through your meter, but the actual energy density of that gas can change based on temperature, pressure, and chemical makeup. To ensure you are only paying for the usable heat you receive, the utility applies a conversion factor to turn that volume into Therms. One Therm equals exactly 100,000 BTUs of heating energy.

Question 5

How many Joules are in one Kilowatt-hour (kWh)?

Accepted Answer

There are exactly 3,600,000 Joules in one Kilowatt-hour. This is derived from the fundamental definition of the units. One Watt equals one Joule per second. A Kilowatt is 1,000 Watts, meaning 1,000 Joules per second. Because there are 3,600 seconds in one hour, multiplying 1,000 Joules/second by 3,600 seconds yields exactly 3.6 million Joules.

Question 6

Why do food labels use Calories instead of Joules?

Accepted Answer

The use of the Calorie is a historical holdover from early 19th-century chemistry. While most of the world uses the kilojoule (kJ) alongside the Calorie on food packaging, the United States strictly adheres to the "Calorie" (which is technically a kilocalorie, or 4,184 Joules) for consumer familiarity. It is simply a legacy marketing and regulatory standard that has proven too entrenched in the public consciousness to change.

Question 7

Can I convert electrical Volts directly into Joules or Watts?

Accepted Answer

No, you cannot convert Volts directly into Joules or Watts without additional information. Voltage is merely the electrical pressure in a system; it is not a measure of energy or power. To find Power (Watts), you must multiply the Voltage by the Current (Amps). To find Energy (Joules), you must multiply the Power by the amount of Time the current flows. Voltage alone does not tell you how much energy is present.

Question 8

What is an Electron-volt (eV) and when is it used?

Accepted Answer

An Electron-volt is an incredibly minuscule unit of energy used almost exclusively in quantum mechanics, solid-state physics, and particle acceleration. It is defined as the amount of kinetic energy gained by a single electron moving across an electric potential difference of one volt. Because it is equal to roughly 1.602 × 10^-19 Joules, it allows physicists to write manageable numbers when calculating the energy of subatomic particles, rather than dealing with infinitesimally small fractions of a Joule.

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