A 600-W TV Receiver Is Turned On For 4 h With Nobody Watching It

A 600-W TV receiver is turned on for 4 h with
nobody watching it. If electricity costs 10 cents/kWh,
how much money is wasted?

So this is a problem that we have taken from the book Fundamentals Of Electrical Circuits By Alexander. But if you want to take a look at the problem yourself, then go to Chapter 1 question 1.39 of the book.

Solve Fundamentals Of Electrical Circuits Problem 1.39 - A 600-W TV receiver
Solve Fundamentals Of Electrical Circuits Problem 1.39 – “A 600-W TV receiver”

Since this is a problem we have taken from the Chapter 1 – Basic Concepts, it should be easy. But is that right? Well, let us see as we try to solve it, shall we?

So how do we go about solving this problem?

Well as we always do, we will first break the problem into small parts. By doing that, we will be in a better position to understand the problem in the first place. Right?

So, here is our breakdown of the problem.

The Problem Breakdown

So let us read out the problem once again, line by line. Alright?

Now the first line of the question reads – “A 600-W TV receiver is turned on for 4 h with nobody watching it.

So what do we learn from that? It means that we have a TV which consumes electricity at 600 Watts Per Hour or 600 Watt/Hr. But we can also write this as 0.6 Kilo Watts Per Hour or 0.6KW/Hr, right? So that means:

P = 0.6 KW/Hour

Ok! So with that being clear, we will move on to our next part of the question which reads – “If electricity costs 10 cents/kWh, how much money is wasted?”

From this sentence, we now know that the cost of 1 KW of Power consumption for every hour is 10 cents.

Electricity Price = 10c/KW

So the question after that then becomes quite simple, isn’t it? It is just asking us to find out what will be the electricity bill for running that A 600-W TV receiver for 4 hours.

A 600-W TV receiver Electricity Cost In 4 Hours?

So solving this now becomes a simple equation:

Total Bill = Power Consumed By TV in 4 hours * Elec. Price

So then what is the total Power consumed by the TV in 4 hours? It is simple right? If the TV consumes 0.6KW in 1 hour, then the amount of Power it consumes in 4 hours is:

Power consumed in 4 hours = 0.6KW * 4 = 2.4KW

So it is now clear right? The TV has consumed 2.4KW in 4 hours. So then what will be the electricity price for this much of power?

Total Bill = 2.4KW * 10 cents => $0.24


What Is An Electrical Circuit – Explained For Dummies

Have you ever tried to look inside an electronic device? If you have, then we are sure that you have come across an electrical circuit. Right? But ever wonder what an electrical circuit is? What it does and why we use them?

No? Then this is an article you should read to get a some idea about it. Since you are new to an electrical circuit, we will try to keep it simple so that it is easy for you to understand. Sounds good? Great! Then let us get started, shall we?

Introduction To An Electrical Circuit

Definition Of An Electrical Circuit

The text book definition of an electrical circuit goes something like this:

It is an interconnection of electrical elements used to transmit power.

But I know that this will not help you understand much as it is quite vague. Right? So let me explain to you about it in simple words.

Electric Circuit Explained In Simple Terms

We know what an electricity is, right? It is the energy source to run many of our every day equipment like TV, Radio, Laptops, Fans, AC etc.

But here is the problem. We don’t normally generate electricity in our houses (Unless your house is solar powered). So where is it generated then? Usually in the Power generation units located in a far off place like water falls, Nuclear plants etc.

So then how do we get this electricity delivered to our houses? Well that is when we use the power lines, right?

But even after you get your electricity to your homes through power lines, it is still not good to run your electrical devices. Why, you ask?

Well that is because the power supplied to our homes are quite high – usually between 100V to 240V. But our electrical devices like laptops or fans dont really need that much of power. Then what do we do?

That is when we make use of an electrical circuit!

Using electrical circuits, we will transfer power to our devices at the right amount that it requires. So in other words, we make use of electrical circuits to transfer the electrical power to a device at the right level.

So what is an electrical circuit made of? Want to take a guess? I did tell you about it already once. Not sure?

Well look at the definition above and tell me. What do you see?

If you said “Electrical elements” then you go it right!

What Are Electrical Elements?

So an electrical circuit contains electrical elements in it. You are clear about that, right? But what are these elements? I never told you about it, isn’t it?

Well, we have many type of electrical in use. And each one of these elements have their own purpose in a circuit. But to give you an idea, here are some examples of electrical elements in use:

  • Resistors
  • Capacitors
  • Inductors
  • Diodes
  • Transistors
  • Transformers etc

So as you can see, we have a lot of elements to use in an electrical circuit. But why do we have so many of them? Well, it is because each of the element have their own set of functionalities. So depending on what we need, we will pick up the right element in our circuit.

Sounds good so far? Great. That is all there is to it. But, before I end this article, let me show you a simple electrical circuit as an example. By looking into it, you will get a good idea about what we are dealing with. Right?

So take a look at this simple circuit where we have an LED light connected through a resistor, capacitor and few other elements. Now I will not go in detail about how it works and all. That should be a separate article by itself in the future.

But this should give you a good mental picture of how an electrical circuit looks like. Take a look at it!

A Simple Electrical Circuit Example
A Simple Electrical Circuit Example


So that is how an electrical circuit looks like. By now, I hope you have got a good idea about what an electrical circuit is and why we need to use it.

If you still have any doubts about it, do let me know in the comments below. I will be more than happy to help you guys out!

So until next time, happy learning! 🙂

Learn the difference between a serial and parallel electrical circuit.