Chapter 11 Flashcards
How can an insulator be charged
By friction through the transfer of electrons
What happens to a material gaining electrons
It becomes negatively charged
What happens to a material losing electrons
It becomes positively charged
What do same charges do
repel
what do opposite charges do
attract
How can electrostatic shock occur
If you are electrically ‘charged’ and you touch something that is earthed or if you’re earthed (completes circuit) and you touch something that is charged the current passes through living material and causes an electric shock
In static electricity, what does it mean to be earthed
Connected to the ground directly or indirectly so the electric charge flows from an object, preventing a dangerous build- up of static electricity.
How does lightening occur
Static electricity building up in clouds which causes spark to form between ground and cloud. Lightening is caused by a flow of charge through the atmosphere.
How does attraction by induction occur, give example
A polythene rod is negativity charged prior by vigorously rubbing it with a cloth. Its the placed over pieces of paper. The paper sticks to the rod. This is because when the negatively charged polythene is brought close to the paper, the negative electrons in the paper are repelled downwards. The upper side of the paper becomes positively charged and therefore the 2 are attracted to each other.
How does earthing remove excess charge by movement of electrons
The excess charge is balanced by the transfer of electrons between the charged object and the ground.
What are some of the everyday uses of electrostatic charges in everyday situations
Photocopiers, defibrillators and paint sprayers.
Insecticide sprayers= They can be sprayed from aircraft so that they cover a large area. There is a risk that some of the spray will blow away or fall unevenly. To prevent this, the insecticide is given a static charge as it leaves the air craft. The static drops evenly as they all have the same charge and are attracted to the earth.
What is an electric field
A region where an electric charge experiences a force
What are some dangers of sparking in everyday situations
Static is dangerous when fueling cars as there are inflammable gases, vapours or a high concentration of oxygen. A spark could ignite the gases and cause an explosion.
Static can be dangerous when you touch something with a large electric charge on it. The charge will flow through your body causing an electric shock. This could cause burns or even stop your heart.
Describe the shape and direction of the electric field around a point charge
The pattern of lines is referred to as electric field lines. They point in the direction that a positive charge would cause if placed upon the line. Therefore if the lines are directed away from centre they are positive and if they are directed inwards they are negative
Describe shape and direction of the electric field between parallel plates
Placing 2 oppositely charged plates parallel to each other creates a uniform electric field. A charge would experience the same force of attraction or repulsion matter where it is located in the field= force is equal at all points in field
Describe shape and direction of the electric field relating to the concentration of lines.
The direction of the arrows shows the direction in which a positively charged particle will move. The spacing between the field lines gives an indication of the strength of the force. If the lines are close together then force will be greater.
How does the concept of an electric field help explain the phenomena of static electricity
x
What’s a permanent magnet
Magnetic all the time eg- fridge magnet
