Electric Discharge Chapter 10

What is It? Rapid transfer of excess charge from one object to another Can sometimes be seen as sparks The greater the imbalance of charge, the greater the discharge

So what’s the problem? When electric discharge occurs, the temperature of the air around the discharge increases This can cause burns to skin Large discharges can also damage electronic equipment

Lightning – Dramatic Discharge! Electrons are constantly being removed from the earth’s surface The negative charges tend to collect at the bottom of the clouds and the positive charges at the top of the clouds This results in a charge separation in the clouds

Lightning – Dramatic Discharge! Electrons on the ground are repelled by the negative charge on the bottom of the clouds This results in a positive charge on the ground below the cloud Electrons are attracted to this positive charge and find the path of least resistance to the ground That is why lightning is often jagged

Lightning Rods Conductors, such as metal structures, are often struck because they provide a path of least resistance Metal lightning rods are placed on buildings to provide a safe path to the ground for the lightning Without these, a lightning strike would cause serious structural damage

Lightning Safety - Inside Stay away from conductors (electrical appliances, telephones, water, plumbing) Shut off all electronics

Lightning Safety - Outside Get in a car Get away from trees Stay low, with as little of your body in contact with the ground as possible

Lightning: Myth or Fact? Lightning never strikes in the same place twice.

Myth! Lightning often strikes the same place repeatedly, especially if it is a tall, pointed, isolated, object.

The CN Tower in Toronto gets hit by lightning about 75 times a year!

Lightning: Myth or Fact? If it is not raining, you’re safe from lightning.

Myth! Lightning can strike from as far away as 25 km from the area of rain.

Lightning: Myth or Fact? Getting in a vehicle with rubber tires will not protect you during a thunderstorm.

Fact! It’s the metal roof and metal sides that protect you. A motorcycle or convertible will not protect you at all!

Lightning: Myth or Fact? It is perfectly safe to touch a lightning victim to give them first aid. You will not be electrocuted.

Fact! The human body does not store electricity. However, do not touch a victim if the charging object is still touching them!

Lightning: Myth or Fact? If outside in a thunderstorm, go under a tree to stay dry.

Myth! Being under a tree is the second leading cause of lightning strikes for humans.

Lightning: Myth or Fact? Wearing metal on your body will attract lightning.

Myth! Metal doesn’t attract lightning. Lightning simply takes the quickest and easiest route to the ground.

Lightning: Myth or Fact? If outside when lightning is about to strike, lie flat on the ground so you are as low as you can get.

Myth! Lightning currents can travel across the ground for over 30 metres. Make as little contact with the ground as possible.

Lightning: Myth or Fact? If you get struck by lightning, you will most likely die.

Myth! Only 20% of people struck by lightning die as a result.

Did you know that…. A single lightning bolt is 5X hotter than the surface of the sun.

Did you know that…. Lightning causes objects to explode because it instantly turns any water to steam.

Did you know that…. The average lightning bolt is about 10 km long

Did you know that…. You have a better chance of being struck by lightning than you do of winning the lottery.

Did you know that…. Around the world, there are about 8 million lightning strikes/day.

Did you know that…. Windsor, Ontario gets more lightning strikes/km2 than any other city in Canada

Did you know that…. The fear of lightning is called kernaunophobia The fear of thunder is called brontophobia

Did you know that….. The fear of homework is called gradophobia But do it anyway! Page 420 # 1, 2, https://www.youtube.com/watch?v=4niTlOYYRYI