How Does Galileo's Telescope Work?

A Bit of History:

Galileo Galilei didn’t invent the telescope. Even so, it was when the great Italian scientist pointed a telescope toward the night (and even the day) sky that the world changed forever.

Galileo discovered the planet Venus has phases, just like the Moon. No one could have known that until the telescope was invented. Galileo saw that the Moon had craters and mountains, and that the Sun had moving black spots on its face. He also discovered four new moons circling the planet Jupiter.

All these discoveries helped show that the Earth is not the centre of the universe, that the planets orbit a changing and imperfect Sun, and that the planets are other worlds, something like the Earth but very far away. With his telescope, Galileo literally remade the world.

Galileo’s telescope was a refracting telescope. Isaac Newton, who was born the same day Galileo died, invented another kind of telescope, called a reflecting telescope. Reflecting telescopes use mirrors instead of lenses to make faraway things look bigger. Reflecting telescopes can be made much more powerful than refractors, and Newton’s invention paved the way for all the great telescopes to come.

How It Works:
Refracting telescopes depend on one amazing fact. As light passes through glass, it slows down. Slowing down a light beam makes it bend. Why? Imagine you’re pulling a wagon along a sidewalk, when the wheels on one side slip off into the grass. The wheels turn slower in the grass than they do on the sidewalk, and the wagon moves toward the grass. In the same way, when a light beam passes through a glass lens inside a telescope, it moves toward the lens. When the light beam comes out the other side, it’s bent!

The shape of the lens means light near the top of the lens is bent down and light near the bottom of the lens is bent up. Somewhere inside the tube the light beams cross, but before they can spread out again the eyepiece lens bends the light beams again and sends them to the eye.

Because the light beams cross, the image ends up upside-down. This doesn’t matter much when you’re looking at Mars or the Moon (remember there’s no real up or down in space), but refracting telescopes used to see objects here on Earth often have another set of lenses to flip the image right-side up again.

Refracting telescopes are simpler than reflecting telescopes, but they have an important limitation. Remember that the light passing through the glass lens gets bent. It turns out that different colours are bent different amounts, and that causes the light to become unfocused. Isaac Newton solved this problem by replacing the lenses with mirrors.

When light hits a mirror, it doesn’t bend. Instead, it bounces off. Just like a ball bouncing off a wall, a light beam comes off a mirror the same way it comes in. In other words, the angle in equals the angle out. And that rule is true for all the light, no matter its colour.

The primary mirror in a reflecting telescope is curved just the right amount to bounce all the light onto the secondary mirror. From there, the light passes through the eyepiece lens, which bends the light into the eye.

How Speakers Work

How Speakers Work

Driver Types:

In the last section, we saw that traditional speakers produce sound by pushing and pulling an electromagnet attached to a flexible cone. Although drivers are all based on the same concept, there is a wide range in driver size and power. The basic driver types are:

1.Woofers
2.Tweeters
3.Midrange

Woofer

Tweeter

Midrange

Woofers are the biggest drivers, and are designed to produce low frequency sounds. Tweeters are much smaller units, designed to produce the highest frequencies. Midrange speakers produce a range of frequencies in the middle of the sound spectrum.

And if you think about it, this makes perfect sense. To create higher frequency waves -- waves in which the points of high pressure and low pressure are closer together -- the driver diaphragm must vibrate more quickly. This is harder to do with a large cone because of the mass of the cone. Conversely, it's harder to get a small driver to vibrate slowly enough to produce very low frequency sounds. It's more suited to rapid movement.

How Wind Power Works?

It's hard sometimes to imagine air as a fluid. It just seems so ... invisible. But air is a fluid like any other except that its particles are in gas form instead of liquid. And when air moves quickly, in the form of wind, those particles are moving quickly. Motion means kinetic energy, which can be captured, just like the energy in moving water can be captured by the turbine in a hydroelectric dams. In the case of a wind-electric turbine, the turbine blades are designed to capture the kinetic energy in wind. The rest is nearly identical to a hydroelectric setup: When the turbine blades capture wind energy and start moving, they spin a shaft that leads from the hub of the rotor to a generator. The generator turns that rotational energy into electricity. At its essence, generating electricity from the wind is all about transferring energy from one medium to another.

Wind power all starts with the sun. When the sun heats up a certain area of land, the air around that land mass absorbs some of that heat. At a certain temperature, that hotter air begins to rise very quickly because a given volume of hot air is lighter than an equal volume of cooler air. Faster-moving (hotter) air particles exert more pressure than slower-moving particles, so it takes fewer of them to maintain the normal air pressure at a given elevation (see How Hot Air Baloons Work) to learn more about air temperature and pressure). When that lighter hot air suddenly rises, cooler air flows quickly in to fill the gap the hot air leaves behind. That air rushing in to fill the gap is wind.

­If you place an object like a rotor blade in the path of that wind, the wind will push on it, transferring some of its own energy of motion to the blade. This is how a wind turbine captures energy from the wind. The same thing happens with a sail boat. When moving air pushes on the barrier of the sail, it causes the boat to move. The wind has transferred its own energy of motion to the sailboat.

How Nuclear Bombs Work?

You­ have pr­obably read in history books about the atomic bombs used in World War II. You may also have seen fictional movies where nuclear weapons were launched or detonated (Fail Safe, Dr. Stragelove, The Day After, Teastament, Fat Man and Littel Boy, The Peace Maker, just to name a few). They're on TV, too -- Jack Bauer struggles to stop a nuclear bomb detonation on the ­TV show "24." In the news, while many countries have been negotiating to disarm their arsenals of nuclear weapons, other countries have been developing nuclear weapons programs.

We have seen that these devices have incredible destructive power, but how do they work? In this article, you will learn about the physics that makes a nuclear bomb so powerful, how nuclear bombs are designed and what happens after a nuclear explosion.

­Nuclear bombs involve the forces, strong and weak, that hold the nucleus of an atom together, especially atoms with unstable nuclei. There are two basic ways that nuclear energy can be released from an atom:

Nuclear fission - You can split the nucleus of an atom into two smaller fragments with a neutron. This method usually involves isotopes of uranium (uranium-235, uranium-233) or plutonium-239.

Nuclear fusion -You can bring two smaller atoms, usually hydrogen or hydrogen isotopes (deuterium, tritium), together to form a larger one (helium or helium isotopes); this is how the sun produces energy

In either process, fission or fusion, large amounts of heat energy and radiation are given off.

To build an atomic bomb, you need:

A source of fissionable or fusionable fuel
A triggering device
A way to allow the majority of fuel to fission or fuse before the explosion occurs (otherwise the bomb will fizzle out)

How Does Bluetooth Work?

Bluetooth is a short range wireless-based open protocol that is used to connect Bluetooth enabled electronic devices. This allows quick and easy synchronization and data transfer.

Bluetooth offers worldwide compatibility as the Bluetooth radio chip, which is built into a small microchip, functions in a globally available frequency band. There is no cabling involved and files, photos and other information are easily exchanged between the connected electronic devices. The connected devices, which may include cellular phones, laptops, personal computers, printers, digital cameras, GPS receivers and even gaming consoles, communicate and exchange data through a secure 2.4GHz to 2.485GHz short range radio frequency bandwidth. Users can, therefore, create Personal Area Netwoks, or PANs for connecting with other Bluetooth compatible devices.
Bluetooth was designed keeping in mind the requirement to operate and allow sharing of data and information exchange in noisy environments where there may be interference from other radio frequency signals such as those from microwave ovens. The radio technology made use of is named frequency-hopping spread spectrum. This technology makes the link between the connected devices a very robust one.

How Hybrid Cars Work

Have you pulled your car up to the gas pump lately and been shocked by the high price of gasoline? As the pump clicked past $20, $30, $40 or even $50, maybe you thought about trading in your car for something that gets better mileage. Or maybe you're worried that your car is contributing to the greenhouse effect.
The auto industry has the technology to address these concerns. It's the hybrid car. There are a lot of hybrid models on the market these days, and most automobile manufacturers have announced plans to manufacture their own versions.
How does a hybrid automobile work? What goes on under the hood to give you 20 or 30 more miles per gallon than the standard automobile? And does it pollute less just because it gets better gas mileage? In this article, we'll help you understand how this technology works, and we'll even give you some tips on how to drive a hybrid car for maximum efficiency.

Hybrid cars like the 2007 Honda Civic Hybrid are designed for fuel efficiency and low emissions.

­­Many people have probably owned a hybrid vehicle at some point. For example, a mo-ped (a motorized pedal bike) is a type of hybrid because it combines the power of a gasoline engine with the pedal power of its rider. In fact, hybrid vehicles are all around us. Most of the locomotives we see pulling trains are diesel-electric hybrids. Cities like Seattle have diesel-electric buses -- these can draw electric power from overhead wires or run on diesel when they are away from the wires. Giant mining trucks are often diesel-electric hybrids. Submarines are also hybrid vehicles -- some are nuclear-electric and some are diesel-electric. Any vehicle that combines two or more sources of power that can directly or indirectly provide propulsion power is a hybrid. Most hybrid cars on the road right now are gasoline-electric hybrids, although French car maker PSA Peugeot Citroen has two diesel-electric hybrid cars in the works. Since gasoline hybrids are the kind you'll find at your local car dealership, we'll focus on those in this article.