Knowledge N Fact4u

How do geologists use carbon dating to find the age of rocks ? •Geologists do not use carbon-based radiometric dating to determine the age of rocks.  •Carbon dating only works for objects that are younger than about 50,000 years, and most rocks of interest are older than that. •Carbon dating is used by archeologists to date trees, plants, and animal remains; as well as human artifacts made from wood and leather; because these items are generally younger than 50,000 years. •Carbon is found in different forms in the environment – mainly in the stable form of carbon-12 and the unstable form of carbon-14.  •Over time, carbon-14 decays radioactively and turns into nitrogen. •A living organism takes in both carbon-12 and carbon-14 from the environment in the same relative proportion that they existed naturally.  •Once the organism dies, it stops replenishing its carbon supply, and the total carbon-14 content in the organism slowly disappears.  •Scientists can de...

Clouds are just water vapor , so why do they move ? •Clouds are not water vapor. Water vapor is the gas state of H 2 O and is invisible.  •The air around you on a humid summer day is chock full of water vapor, but you don't see any of it.  •On the other hand, there is very little water vapor in the air during the cold of winter, yet you can easily make clouds with your breath.  •Clouds are collections of liquid water droplets or ice that are small enough to float.  •When the water vapor in the air gets cold enough, it condenses back into liquid in the forms of droplets.  •But the condensation is not automatic. It takes a bit of matter – a condensation nucleus – in order to jump start the process. Dust, salt, and ice in the air do the trick by providing a surface for the water to condense on to.  •Clouds are white because the water droplets making the cloud are the right size to scatter light resonantly according to Mie scattering.  •Mie scatte...

Why do car tires protect you from lightning strikes ? •Car tires do not protect you from lightning strikes. Although the rubber in a tire acts as an insulator at low voltages, the voltage in a lighting bolt is far too high to be stopped by tires or air.  •No matter how thick your tires are, they don't stop lightning, according to scientists. •A study states that inside a car can be a safe place to wait out a lighting storm, but it's not because any materials are blocking the lightning. •Rather, if the car is struck by lightning, its metal frame redirects the electrical current around the sides of the car and into the ground without touching the interior contents.  •The ability of a hollow conducting object to protect its interior from electrical fields and currents is one of the fundamental principles of electromagnetics.  •Such an object is called a Faraday cage. For this reason, riding around in a convertible, on a motorbike or on a bicycle duri...

Why is the sky not blue as seen from space ? •The daytime sky is indeed blue as seen from space. Look closely at any color-accurate photograph of earth taken from space and the blue tint of everything on the day side is unmistakable. This blue tint is the sky. •The daytime sky as viewed from space is not a solid, uniform blob of blue for two reasons: (1) there are white clouds in the sky which can be seen just as well from space as from earth's surface, and (2) the sky is not opaque. •Earth's atmosphere consists mostly of nitrogen molecules and oxygen molecules bouncing around as a gas.  •Air is close to perfectly transparent. It's a good thing, because the transparency of air is what allows you to see your computer screen and breath at the same time.  •However, air is not perfectly transparent. A very small amount of the light that passes through air is scattered in all directions instead of being allowed to continue traveling on in the forward directi...

Does the back of a rainbow look the same as its front side ? •A rainbow does not have a back side. If you were to walk completely to the other side of the mist cloud that is creating the rainbow and turn around, you would not see a rainbow.  •You have to realize that a rainbow is not a stationary physical object. Instead, it is a pattern of light that becomes a stable image only when you look at it from the right angle.  •You may not have noticed it, but every time you look directly at the center of a rainbow, the sun is directly behind your head. This is the only angle at which the light pattern that constitutes the rainbow can enter your eye and therefore lead you to see it. •The sun is always in the opposite part of the sky from the center of the rainbow. This is because a rainbow is actually just sunlight which has been refracted and reflected.  •Refraction occurs when the sunlight enters and leaves the small spherical water droplets that co...