This time, I wanted to do something a little different and hopefully a little fun.

This post isn’t a post in the sense that it’s a tutorial on a certain topic.

This post is a short electronics quiz to assess your knowledge, maybe learn something along the way, and most of all, have some fun.

The questions in this set aren’t engineering level questions (in other words, they’re not terribly difficult) but some of them may be a little challenging depending on your knowledge and experience.

Don’t worry if this particular quiz didn’t contain a question about a certain topic. There are a myriad of questions one can ask concerning electronics, programming, circuit design, and much more. Rather, keep visiting the blog or subscribe via RSS as I’ll be posting more quizzes like this in the future.

First, you’ll see the questions.

After the last question, I’ll post the answers to each question with an explanation (or I’ll work the problem out, if appropriate).

No peeking!

Now let’s test your electrical knowledge…

**Electronics Quiz**

1) Imagine an infinite grid of 1 Ohm resistors connected together (like the one in the picture below). If you were able to measure the total resistance of this grid, what would it be?

2) True or false: it takes more heat to melt lead-free solder than regular solder.

3) What is the difference between a primary and a secondary battery?

4) Name this component:

5) What is the value of the resistor below?

6) Five amps flow through a 10 Ohm resistor. How much power is dissipated by the resistor?

7) Your hair dryer draws 500 W of power. The electric company is charging you 11 cents per kilowatt-hour. You use the hair dryer for half an hour. How much did that dry head of hair cost you?

8) How many time constants does it take to charge/discharge a capacitor?

9) The sum of currents entering a node (or point in a circuit) is equal to the sum leaving the node. This is referred to as ___________________________.

10) Find V_{x} in the circuit below.

**Answers to Electronics Quiz Questions**

Space below left intentionally, scroll down for answers.

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**1) Answer: 0.**

This is because the resistors are connected in parallel. We know that in any group of resistors connected in parallel, the total resistance is always less than the lowest resistance in the group. Since there is an infinite amount of one Ohm resistors in parallel, the total goes to zero.

**2) Answer: true.**

**3) Answer: primary batteries cannot be recharged.**

I wrote two posts on batteries, one covering primary batteries and another about secondary (rechargeable) batteries.

**4) Answer: photoresistor (a.k.a. photocell, light dependent resistor)**

Photoresistors vary their resistance according to the amount of light that hits them.

**5) Answer: 572 Ohms, 2% tolerance.**

It’s a 5 band resistor with bands colored (left to right) green, violet, red, black, red. The first three bands give the first three digits of the resistor’s value. The fourth (black) is the multiplier and is 0 in this case, so we’re not going to tack on any zeros to our answer of 572 Ohms. The last band is the tolerance which, in this case, is 2%. Check out my post on resistor color code if you need help with this.

**6) Answer: 250 W.**

Ohm’s Law is back to haunt us again. The easiest way to answer this problem is to remember that P = I^{2}R. So, we have 5^{2} x 10 = 250 W. Make sure you use a power resistor if you build a circuit like this!

**7) Answer: 2.75 cents.**

Power companies charge by the kilowatt-hour, so we need to convert watts into kilowatts first. 500 W is equal to 0.5 kW. Since we’re only using the device for half an hour, we need to multiply 0.5 kW by 0.5 hours, then multiply by our cost of 0.11 (11 cents):

0.5 x 0.5 x 0.11 = $0.0275 or 2.75 cents.

**8) Answer: 5.**

The exact reason for this involves differential equations and is somewhat complicated. Maybe I’ll tackle it (and try to simplify it) in a future post. For now just take my word for it 😊

**9) Answer: Kirchhoff’s Current Law (a.k.a. KCL).**

KCL is one of the basic tools for analyzing circuits.

**10) Answer: 95 V.**

This was probably the hardest question here. Using another one of Kirchhoff’s laws (KVL or Kirchhoff’s Voltage Law) to solve for V_{x}, we can write the following equation:

20 + 15(5) – V_{x} = 0

Solving algebraically for V_{x}, we get V_{x} = 95 V.

I’ve booked Mr. Kirchhoff and his laws to make a future appearance on the blog 😉

**How’d you do on the first-ever electronics quiz?**

Since there are only ten questions, I decided to use a different grading scale than the one you’re familiar with from school.

You remember that one. If you scored a 90% or better you got an A. Less than 60% and you failed. And getting a D wasn’t considered great, even though it was a passing grade. That would mean you could only miss three questions and still get a decent score. For some of you, that may be child’s play, for others, maybe not.

Here’s the breakdown I decided to use:

- 1-4 correct: Beginner
- 5-7 correct: Intermediate
- 8-10 correct: uber-geek

Now I just have a few more questions for you…

How did you like this? Were the questions too easy? Were they too hard? Should I have 15 questions instead of 10?

Let me know your thoughts in the comments below.

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