Engineers Week

Engineers Week was last week. One reason the organizers put effort into making and promoting Engineers Week is to get kids interested in engineering. So why does it take place during winter vacation week?

So I'll be belatedly "celebrating" Engineers Week this week by visiting my daughter's elementary school class and talking about electricity. My presentation is titled, "Watt is Electricity?" Get it?

I made a little electromagnet kit for each student. All I did was wind about four feet of solid 22 gauge copper wire around a nail. I placed this in a bag with a D battery, some paper clips and a sheet of paper with this text:

Electromagnet Test Kit
Contains:

• 4’ 22 AWG Solid Insulated Copper Wire
• Steel Nail
• D Battery (1.5V)
• Paperclips (to test electromagnet)
  

When electrical current flows through a wire, a magnetic field develops around the wire. By winding the wire into a tight coil around an iron core, the magnetic flux is concentrated, and the magnetic attraction is strong.

Touch the bare wire ends to the battery terminals.

Watch Out – it gets HOT.

How many paper clips can you pick up?

What do you think would happen if:

• You unwrapped some of the wire?
• You used a 9V or 12V battery?
• You wrapped the wire around a pencil?

Science Links for Kids
http://www.energyquest.ca.gov/projects/
http://www.eia.doe.gov/kids/
http://www.ieee-virtual-museum.org/
http://www.discoverengineering.org/

Those links are pretty cool. Check them out when you get a chance!

More on Traffic Lights

I was too tired to continue my previous post. So I'll add some comments here in a new post.

I wrote:

If the number of cars on the main road is so great that you need to interrupt the flow in order to let yet more cars on it, you're contributing to yet more traffic congestion.

Actually, about 16 years ago, traffic lights were introduced on entrance ramps to the Long Island Expressway. The idea was to prevent cars from entering the highway during rush hour. That demonstrates an appropriate use of traffic lights -- to improve the flow of traffic rather than to impede it.

I wrote:

It's inefficient to force several cars to stop for the sake of one or two cars that are already stopped. Forcing a car to stop and then accelerate back up to cruising speed is a significant waste of gas. In fact every time a driver applies the brake, he or she "throws away" the fuel that was used to accelerate the car. And acceleration is what uses the most fuel.

And...

Many of these intersections are so small that when cars turn onto them from the main road, the cars trigger the Hall effect sensor that causes the light to cycle. Thus, the light turns red for those who navigate the main road even when there's no car to yield to! More waste!

You can solve both problems simply by installing (or moving) the sensors farther back from the intersection and decreasing the sensitivity. That way the light won't cycle unless there are a few cars queued up. It might be a good idea to change the mode to blinking red-yellow during non-peak hours to allow cars to enter the main roadway whenever it's clear, but then have the light switch to give the right-of-way to the smaller roadway when enough cars are waiting.

I can imagine the day when every intersection will have a traffic light. Hopefully I'll be dead by then. Or perhaps traffic lights will be part of a Intelligent Vehicle System that's designed to route traffic for maximum efficiency. Lights will be used to tell motorists when it's safe to enter the intersection rather than stop other cars to allow them to enter.

The Problem With Traffic Lights

"'See, I can time them perfectly,' the [traffic] light said with satisfaction. 'I get hundreds of them each day. No one gets through my intersection without paying his tax in gas and rubber.'"

"'Go blow a bulb!' the car growled at the light.

"'Go soak your horn!' the light flashed back."

- from pages 187 to 188 of "Centaur Aisle," by Piers Anthony

I've had this quote in my "Quote du Jour" for several weeks, ready for the day I finally rant about traffic lights.

In my town, traffic lights are installed indiscriminately as a feeble response to town growth. The rich folks flock to buy McMansions in new developments. Then they complain that they can't get onto the main road without waiting a minute or two for a break in the traffic. So up goes yet another traffic light.

There are intersections where traffic lights are needed, such where two main highways intersect.

But why install one at a "T" intersection on a busy main road for a tiny side street? Here's why it's not a good idea:

• If the number of cars on the main road is so great that you need to interrupt the flow in order to let yet more cars on it, you're contributing to yet more traffic congestion.
• It's inefficient to force several cars to stop for the sake of one or two cars that are already stopped. Forcing a car to stop and then accelerate back up to cruising speed is a significant waste of gas. In fact every time a driver applies the brake, he or she "throws away" the fuel that was used to accelerate the car. And acceleration is what uses the most fuel.
• Many of these intersections are so small that when cars turn onto them from the main road, the cars trigger the Hall effect sensor that causes the light to cycle. Thus, the light turns red for those who navigate the main road even when there's no car to yield to! More waste!
• Finally, traffic lights waste electrical power all day and night. In fact, they remain powered up even in the wee hours of the morning when no one needs them. At night they're so bright you could read a large-print book under them. Why not reduce the light intensity after dark and save money? True, some lights are set to blink red-yellow, and thus they require half the electricity to light the lamps. But the controllers that run them also waste electricity. So just shut them down completely and get that power consumption down to zero. Drivers know anyway to stop before they enter a main road in the absence of traffic control.