Physics -Grade 8 2014 Flashcards
What is static energy?
An electric charge that stays on the surface of an object instead of flowing through it or away
What is electricity?
A form of electricity that results from the interaction of charged particles (ex. protons + electrons)
What does a net positive charge mean?
It means that the object has a lot more protons than electrons and a net negative charge is the opposite of a net positive charge and protons and electrons will always be found on every object.
What is charging by friction?
It is when objects are rubbed together and electrons are transferred. The material with a stronghold will gain electrons from the one with the weaker hold. Only electrons can move between objects. Protons cannot.
What is a static discharge?
It is when charged objects are brought together, and electrons quickly flow from the negatively charged object to the positive or neutrally charged object. It is also known as a shock.
How do you remove a static charge?
Putting a charged object in contact with a ground will neutralize it. A ground can provide or take away a very large amount of electrons. An example of a ground is the earth.
What is charging by contact?
It is when contact is made between a charged object and a neutral object and electrons are transferred.
What are electric fields?
Charged objects have a electric fields which can exert electric forces on objects around them. This is similar to how the Earth exerts gravitational force on the things around it. The strength of the force is proportional to the amount of charge on the objects, and the distance they are away from each other.
What is charging by induction?
When charged objects are brought your neutral objects, they can cause the electrons in the neutral object to move forward move towards or away from the charged object. This is induced charge separation. This can cause a selection of the neutral objects to become charged and attract charged object. If a ground is then used on one of the halves of object, the object will become permanently changed.
How is lightning created?
Is created by charging through fiction. Smaller water droplets and ice particles inside the cloud are carried up by air currents. Heavier water droplets and hail fall through the cloud because of gravity. The two groups collide and rub against each other. Electrons are transferred to the hail and large water droplets. Negative charge builds up at the bottom of the cloud, as the charge builds up, it induces a positive charge separation on the ground below. The attraction between the charges causes an ion channel to be formed from the cloud. This consists of ionized gases. The channels link and form a conductive chain between the cloud and the ground, and a huge amount of electrons (energy) are transferred down the path. Typically strikes taller objects since it requires a shorter path.
What is thunder?
The superheating of the air along this channel causes air to expand and creates a shockwave which radiates out from the lightning.
What are the types of lightning?
- Cloud to ground. 2. Cloud to cloud (sheet) lightning. 3. Upper atmospheric lightning. 4. Dry lightning.
What are lightning rods? How are they used?
Lightning rods are conductive rods which are placed on the highest points of buildings, and are attached by cable to the ground. They protect buildings and people from lightning. Lightning will likely hit the rod, and electrons will flow to the ground at through the cable. Rods also decrease the chance of a storm by helping to equalize the charge difference in a cloud.
What are electric circuits?
A close conductive path along which electrons flow. Electrons are made to flow by a power source in the circuit. The power source provides electrical energy.
What is a voltaic cell?
It is a cell which generates current by chemical reactions involving two different materials separated by conductive solution (electrolyte).
