Friday, 9 December 2011

Light


Light travel in straight line

Electricity

                                                                       Electricity

Fun facts about electricity

Fun Facts About Electricity
  • Lightning striking a pole near a houseElectricity travels at the speed of light - more than 186,000 miles per second!
  • A spark of static electricity can measure up to three thousand (3,000) volts.
  • A bolt of lightning can measure up to three million (3,000,000) volts - and it lasts less than one second!
  • Electricity always tries to find the easiest path to the ground.
  • Electricity can be made from wind, water, the sun and even animal manure.
  • Burning coal is the most common way electricity is made in the United States.
  • One power plant can produce enough electricity for 180,000 homes.
  • The first power plant - owned by Thomas Edison - opened in New York City in 1882.
  • Thomas Edison didn't invent the first light bulb - but he did invent one that stayed lit for more than a few seconds.
  • Thomas Edison invented more than 2,000 new products, including almost everything needed for us to use electricity in our homes: switches, fuses, sockets and meters.
  • Benjamin Franklin didn't discover electricity - but he did prove that lightning is a form of electrical energy

Electricity


Force and energy

Forces of Nature

The gravitational pull o fthe Sun is only one type of force. Forces are a big part of physics. Physicists devote a lot of time to the study of forces that are found everywhere in the universe. The forces could be big, such as the pull of a star on a planet. The forces could also be very small, such as the pull of a nucleus on an electron. Forces are acting everywhere in the universe at all times.

Examples of Force

If you were a ball sitting on a field and someone kicked you, a force would have acted on you. As a result, you would go bouncing down the field. There are often many forces at work. Physicists might not study them all at the same time, but even if you were standing in one place, you would have many forces acting on you. Those forces would include gravity, the force of air particles hitting your body from all directions (as well as from wind), and the force being exerted by the ground (called the normal force).

The force of gravity causes the ball to return to the surface. Let's look at the forces acting on that soccer ball before you kicked it. As it sat there, the force of gravity was keeping it on the ground, while the ground pushed upward, supporting the ball. On a molecular level, the surface of the ball was holding itself together as the gas inside of the ball tried to escape. There may have also been small forces trying to push it as the wind blew. Those forces were too small to get it rolling, but they were there. And you never know what was under the ball. Maybe an insect was stuck under the ball trying to push it up. That's another force to consider.

If there is more than one force acting on an object, the forces can be added up if they act in the same direction, or subtracted if they act in opposition. Scientists measure forces in units called Newtons. When you start doing physics problems in class, you may read that the force applied to the soccer ball (from the kick) could be equal to 12 Newtons.

Force and energy

Forces of Nature

The gravitational pull o fthe Sun is only one type of force. Forces are a big part of physics. Physicists devote a lot of time to the study of forces that are found everywhere in the universe. The forces could be big, such as the pull of a star on a planet. The forces could also be very small, such as the pull of a nucleus on an electron. Forces are acting everywhere in the universe at all times.

Examples of Force

If you were a ball sitting on a field and someone kicked you, a force would have acted on you. As a result, you would go bouncing down the field. There are often many forces at work. Physicists might not study them all at the same time, but even if you were standing in one place, you would have many forces acting on you. Those forces would include gravity, the force of air particles hitting your body from all directions (as well as from wind), and the force being exerted by the ground (called the normal force).

The force of gravity causes the ball to return to the surface. Let's look at the forces acting on that soccer ball before you kicked it. As it sat there, the force of gravity was keeping it on the ground, while the ground pushed upward, supporting the ball. On a molecular level, the surface of the ball was holding itself together as the gas inside of the ball tried to escape. There may have also been small forces trying to push it as the wind blew. Those forces were too small to get it rolling, but they were there. And you never know what was under the ball. Maybe an insect was stuck under the ball trying to push it up. That's another force to consider.

If there is more than one force acting on an object, the forces can be added up if they act in the same direction, or subtracted if they act in opposition. Scientists measure forces in units called Newtons. When you start doing physics problems in class, you may read that the force applied to the soccer ball (from the kick) could be equal to 12 Newtons.

Investigating force and energy