In this article, we will get familiar with the concepts of Electrical Energy as well as Electric Power. First, we will know what electrical energy is and how it is produced. We will then discuss the SI units associated with it, the symbols used for the units, and basic conversions using simple equations. After that, we will introduce electric power, which describes how fast electrical energy or converted to other types of energy, and we will also discuss the units, symbols, and equations related to electric power. To understand these concepts clearly we will solve some examples to explain how the concept of electric power and energy is used in practical situations.
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Electrical Energy can be defined as the energy produced by the movement of electrons from one point to another. It is a type of kinetic energy as it involves the motion of charged particles. The movement of charged particles creates current or electricity.
The SI unit of electrical energy is the joule (J).
One joule is defined as the amount of energy used when a current of one ampere flows through a resistance of one ohm for one second. In terms of electrical power:
1 joule $=1$ watt $\times 1$ second
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The formula to calculate electrical energy is:
$$
E=P \times t
$$
Where:
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Here are some common examples of Electrical energy in everyday life:
Below table describes the electrical Energy in the summarised form for easy understanding.
Symbol of electrical energy | E |
Unit of electrical energy | Joule (J) |
Kilowatt-hour(kWh) | |
Electron-Volt(eV) | |
Formula of electrical energy | E = QV Where, Q is charged V potential difference |
Examples of electrical energy | Electricity prices go by telephone or electricity. |
Lightning. | |
Batteries. | |
Consistent electricity. | |
Electric wheels produce electrical energy. | |
Electricity is stored in capacitors. | |
Audio speakers. | |
Doorbells. | |
Uses of electrical energy | Lighting, cooling, heating. Operating equipment, electronics, computers, and equipment. Public transportation plans. |
Now let's discuss the concept of electrical power in detail:
Electric Power is defined as the rate at which work is performed in an electrical circuit. In simple words, we can say that electric power tells us that how fast electrical energy is converted into another form of energy.
The standard unit of electric power is the watt (W).
Formula to calculate electric power is:
$$
P=V \times I
$$
where:
Electric Power can also be calculated using Ohm's Law. The formula to calculate Power using Ohm's law is:
$$
P=I^2 \times R
$$
or
$$
P=\frac{V^2}{R}
$$
where $R$ is the resistance in ohms $(\Omega)$.
Symbol | P |
SI Unit of Electric Power | Watt, joule per second |
Scale or Vector quantity | Scalar Quantity |
Formula | P=VI |
Question 1: A 100-watt bulb is used for 10 hours. Calculate the electrical energy consumed by the bulb in kilowatt-hours ( $\mathbf{( W h ) .}$
Solution:
$$
\begin{gathered}
\text { Power }=100 \mathrm{~W} \\
\text { Time }=10 \text { hours } \\
\text { Energy }(\text { in } \mathrm{kWh})=\frac{\text { Power (in W) } \times \text { Time (in hours) }}{1000} \\
=\frac{100 \times 10}{1000}=1 \mathrm{kWh}
\end{gathered}
$$
So, the electrical energy consumed is 1 kWh .
Question 2: An electric heater has a resistance of $20 \Omega$ and is connected to a 220 V power supply. Calculate the power consumed by the heater.
Solution:
Using the formula $P=\frac{V^2}{R}$,
$$
\begin{gathered}
V=220 \mathrm{~V} \\
R=20 \Omega \\
P=\frac{220^2}{20}=\frac{48400}{20}=2420 \mathrm{~W}
\end{gathered}
$$
The power consumed by the heater is 2420 W.
Question 3: A device operates on a 5 A current and 12 V voltage. Calculate the power consumed by the device and the energy consumed if it runs for 2 hours.
Solution:
Step 1: Calculate power.
$$
P=V \times I=12 \times 5=60 \mathrm{~W}
$$
Step 2: Calculate energy in kWh.
$$
\text { Energy }=\frac{P \times \text { Time }}{1000}=\frac{60 \times 2}{1000}=0.12 \mathrm{kWh}
$$
The power consumed is 60 W , and the energy consumed is 0.12 kWh .
Electrical energy can be caused by kinetic energy or potential energy. It is largely due to potential energy, which is energy stored due to positions associated with charged particles or electric fields. The SI unit of power is watts, one joule per second.
Electrical units joules, kilowatt hour, electron-volt
Electricity measurement rate of power transmission per circuit at each time point.
The SI unit of Electric Power of electricity is watt.
Examples of electrical energy are lightning, batteries, and even electric eels.
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