Sciencee xx

• Our lives will not be the same without electricity
• We communicate, travel and compute faster because of the devices run by electricity
• An atom is electrically neutral because they have an equal number of protons and electrons
• Following Benjamin Franklin's study of electricity, we call electrical charges positive and negative
• These two types of charges exist in all materials and in all states of matter
• Protons are the carriers of positive charges, neutrons are the uncharged particles, and electrons are the carriers of negative charges
• A force that pushes objects apart is a force of repulsion, it exists between particles of the same charge
• A force that pulls objects together is a force of attraction, it exists between particles of unlike charges
• Negatively charged electrons are attracted to positively charged protons
• The standing of the hair on your arm is the result of static electricity
• Ways to charge an object


  • Friction
  • Conduction
  • Induction
• Charging


  The process of supplying electric charge to an object or losing the electric charge from an object
• Charging by friction


  The process in which an object gets charged when it is rubbed against another object or there is a direct contact between the two objects
• When two objects are rubbed together, one object loses electrons while the other gains electrons
• Charging by conduction


  The process in which an object gets charged by making contact with the charged object
• Conductors


  Materials that allow electrons to move freely, like metals
• Insulators


  Materials that do not allow electrons to flow freely, like rubber, wood, glass, or plastic
• Charging by induction


  The process in which an object gets charged by an object without direct contact, the movement of electrons to one part of an object by the electric field of another object
• A neutral object needs only to come close to a charged object for the leaves of the electroscope to move separately
• More than three quarters of earth's atmosphere is made up of nitrogen while one film is oxygen
• These gases not only produce important weather features such as cloud and rain but also have considerable influence on the overall climate of the earth through the greenhouse effect and global warming
• Greenhouse


  A structure with walls and roofs made chiefly of a transparent material such as plastic or glass, useful in growing seedlings when this winter or spring before planting them in the open field
• Uses of greenhouses


  • Growing seedlings
  • Protecting flowering and ornamental plants from harsh weather conditions and insect attacks in tropical countries
• How greenhouses work


  • Transparent covering allows visible light to enter without obstruction
  • Warms the inside of the greenhouse as energy is absorbed by the plants soil and other things in the building
  • Air warmed by the heat inside is retained in the building by the roof and wall
  • Transparent covering prevents the heat from leaving by reflecting the energy back into the walls and preventing outside winds from carrying it away
• Greenhouse effect


  The process where greenhouse gases trap the heat in the atmosphere
• Global warming


  The current rise in the average temperature of earth's air and oceans
• Sources of greenhouse gas emissions


  • Burning fossil fuels for electricity, heat and transportation
  • Deforestation and land clearing for agriculture
  • Degradation of soils
  • Agricultural activities
  • Waste management
  • Energy use
  • Biomass burning
  • Use of fertilizers
  • Industrial processes
  • Refrigeration
  • Use of consumer products
• Many of these greenhouse gases can cause earth's atmosphere to trap more and more heat, increase air temperature and cause global warming
• Global warming is feared to melt polar ice caps and cause flooding to low-lying areas, resulting in a reduction in biodiversity and changing climates around the globe, causing stronger typhoons and creating many health related problems
• There are a number of unique combinations of atmospheric phenomena experienced by people in all parts of the world
• Wind


  Air that is moving horizontally
• Land surface heats up faster than bodies of water during the day, but land loses heat faster than bodies of water at night
• Sea breeze formation


  1. Land warms up faster than bodies of water during the day

  2. Warm air above land rises

  3. Cooler air above the sea moves toward the land and replaces the warm air
• Land breeze formation


  1. Land cools faster than the sea at night

  2. Warm air over the sea rises

  3. Cooler air from the land moves toward the sea
• Monsoon formation


  1. Air moves toward the place where warm air is rising (low pressure area)

  2. Cold air sinks in the high pressure area

  3. Wind moves from high pressure to low pressure area
• Northeast monsoon


  • High pressure in China and Siberia, low pressure in South Indian Ocean/Australia
  • Brings dry, cold wind
• Intertropical Convergence Zone (ITCZ)


  • Place where trade winds from Northern and Southern hemispheres meet at the equator
  • Warm, humid air masses form resulting in heavy precipitation and thunderstorms
  • Breeding zone of low pressure areas
• The earth is constantly moving around the sun and the moon is constantly moving around the earth
• Eclipse


  Occurs when the shadow of either the moon or earth is cast on the other
• Straight or nearly straight line formation of the sun, earth, and moon

  Called conjunction