11) Static Electricity Flashcards
What is charge measured in?
Coulombs (C)
When do objects become charged?
When they gain or lose electrons
What happens to like charges?
They repel
What happens to unlike charges?
They attract
What happens to an object that becomes negatively charged?
It gains electrons
What does a difference between the positive and negative charge of two objects cause there to be?
A potential difference between objects
What does the potential difference between two oppositely charged objects cause?
Rapid energy transfer
Spark produced
What causes lightning?
Charge building up in clouds producing a spark
What does rubbing an object do to the electrons?
Electrons can jump from one object to the other
Both objects become charged
How can a plastic rod or balloon be charged?
Rubbing it with a cloth or hair
What can a charged plastic rod attract?
A gentle stream of water from a tap
What can a charged plastic rod move?
An empty aluminium can
Where do conductors allow charge to flow to?
Earth
Why can’t conductors maintain a charge?
The charge flows to Earth
What are isolated objects?
Objects with no conducting path
What are 2 uses of static electricity?
Insecticide spraying
Photocopying
How does insecticide spraying work with static electricity?
1) Insecticide is given an electrostatic charge when released
2) Insecticide then attracted to earth so moves away from the sprayer
3) Repulsion between droplets means they don’t clump together
4) Gives an even layer of insecticide to ground
What are advantages of using static electricity in pesticide spraying?
Less pesticide lost
Evenly distributed
How does photocopying work with static electricity?
Areas to receive ink are positively charged and ink is negatively charged
Ensures even coat of ink in the right places
Why is fuelling a car at risk to sparking?
Fuel pumped through hose rubs against car
Electrostatic charge builds up due to friction
What do imperfections and gaps in fuelling hoses risk?
Charged fuel can escape as vapour
Spark can ignite vapour and cause an explosion
What stops fuel hoses from the risk of sparking?
Earthing the hose
What causes electric shocks?
Touching charged objects cause current to flow from the object to you
What happens to 2 objects in static electricty?
One becomes positive
One becomes negative
What do charged objects create around them?
Electric fields
What happens if an electrically charged object enters an electric field?
It feels the force acting on it
What is the direction of arrows on an electric field diagram?
The direction positively charged objects would move
How does the distance from a charged object affect the strength of the electric field?
The closer to the object, the stronger the electric field
What affect does a higher charged object have on the strength of an electric field?
The electric field will be stronger
What are point charges?
The electric field lines around tiny positively charged and negatively charged objects
How can you see electric fields?
You can’t
