Electrostatics Flashcards
(22 cards)
How do objects become charged?
When they gain or lose electrons
What is charge measured in?
Coulombs (C)
Like charges______ and unlike charges _____
Like charges repel and unlike charges attract
An object that loses electrons becomes ________ charged and an object that gains electrons becomes ________ charged
loses=positively
gains=negatively
How do sparks happen?
When there is a difference between the positive and negative charge of two objects, there is a potential difference between the two objects. This potential difference causes a rapid transfer of charge. Energy is stored in an electrostatic store and a spark is produced.
What is an example of a spark?
Lightning-charge builds up inside the clouds and creates lightning
Suggest why clothes dried in a tumble drier might stick to eachother
The clothes will rub against each other in a tumble drier. This could charge the clothes as electrons are lost when the clothes rub together. Some will lose electrons and become positively charged and others will gain electrons and become negatively charged. The clothes that are oppositely charged will attract eachother and stick together.
Charged objects can ______ on other objects
exert forces
What does rubbing an object against another do?
Can cause elctrons to jump from one object to the other. This causes both objects to become charged.
How can a plastic rod become charged?
-A plastic rod can be charged by rubbing it with a cloth
-The charged rod will attract a gentle stream of water falling from a tap
-The charged rod can move an empty aluminium drink can. The charge on the rod attracts or repels the electrons in the metal, moving the can.
What are isolated objects?
Objects with no conducting path to earth
Why can’t conductors maintain a charge?
Conductors allow flow to earth
How can static electricity be used in photocopying?
The areas to receive ink are positively charged, which ensures an even coat of ink in the right places.
How can static electricity be used with an insecticide sprayer?
-The insecticide is given an electrostatic charge when it is released
-The insecticide is then attracted to the earth so moves away from the sprayer
-There is a repulsion between the droplets of insecticide which means the droplets don’t clump together
-This gives an even layer of insecticide on the ground
What is an example of when sparking is dangerous and why does it happen?
Fuelling cars:
-When fuel is pumped through a hose into a car it rubs against the hose
-This results in an electrostatic charge building up due to friction
-Imperfections in the fuel and gaps in the hose system so charged fuel can escape as vapour
-When gas leaks, a tiny spark can ignite the vapour
Why is it important to earth a hose supplying fuel?
Reduces the risk of sparking happening as it provides a path to the earth for the charge.
What causes electric shocks?
Electric charge sometimes builds up on an object, resulting in a potential difference between you and the charged object. When you touch the object, a current can flow from the object to you, which can be detected by your skin as a sharp pain.
When does static electricity arise?
When electrons transfer from one object to another.
What is an electric field?
-Charged objects create invisible electric fields around themselves
-If another electrically charged object enters an electric field, the charged object will feel a force acting on it
What is the direction of an electric field?
-The direction that a positively charged object would move at that point in the field
-The direction of an electric field is shown on a diagram by arrows drawn onto the electric field lines
The _______ an object is to the charged object, the stronger the electric field and the _______ the charge of the object, the stronger the electric field.
closer, higher
