P3.1 Static Electricity Flashcards
Define: ampere (A)
the unit of current
Define: battery
one or more cells
Define: cell (electricity)
a device that produces a potential difference (separation of charge) from chemical reactions; what people normally call a ‘battery’
Define: conventional current
the model where current flows from positive to negative, opposite to electron flow
Define: coulomb (C)
the unit of charge
Define: current (electric)
the rate of flow of charged particles (usually electrons), current = charge/time
Define: electric charge
a property (like mass) of a particle; it can be positive or negative
Define: electric field
a region produced by charged particles or objects where charged particles of objects experience a force
Define: milliamp (mA)
1 milliamp = 1/1000 amp
Define: spark
the breakdown of air that discharges a charged object; the heating of the air produces light and sound
Define: static electricity
the charge that insulating objects acquire because of the transfer of electrons
A material has to be this if it is to become charged when you rub it
insulator
Objects become charged when these things are transferred.
electrons
We experience static electricity in our everyday lives. Sort the scenarios into two groups:
a) examples of charging and
b) examples of discharging or earthing.
1) using a plastic dusting brush
2) using a defibrillator
3) touching a water pipe
4) rubbing a plastic comb with a cloth
5) fuels flowing through pipes
6) touching a metal door handle
7) a spark in a spark plug in a car
8) walking across a synthetic carpet
a) 1, 4, 5, 8
b) 2, 3 6, 7,
Which three of the following statements about static electricity are correct?
a) If you become charged and then touch a conductor connected to the Earth you get an electrostatic shock.
b) You get a shock from a charged object because the charge cannot flow through you.
c) A lightning bolt happens when the charge built up in a cloud flows to the Earth.
d) You experience an electric shock when charge flows through you to the Earth.
e) An electric shock happens when you become charged up and then touch an insulator.
a, c, d
Which three of the following statements are correct?
a) A rod becomes positively charged when electrons are removed from it.
b) Atoms or molecules that have had electrons transferred to them or from them are called ions.
c) A cloth becomes negatively charged when electrons have been transferred to it.
d) A cloth becomes negatively charged when electrons are removed from it.
e) A rod becomes positively charged when electrons have been transferred to it.
a, b , c
Decide which the statements below are reasons why an electrostatic precipitator works.
a) Charged dust particles are attracted to plates that are either earthed or have the opposite charge to the dust.
b) The heat energy in the smoke or waste gases heats up the metal grids and plates.
c) The dust sticks to the plates inside the chimney and then falls down, making sure that it does not leave the chimney.
d) Dust particles travel through a metal grid and become either positively or negatively charged.
a, c, d
_____ can be removed from chimney smoke using a _____ metal grid to charge up the dust. The dust is then _____ to charged or earthed metal plates on the sides of the chimney and then falls down into a collector.
dust, charged, attracted
If you need to spray a car with paint you can charge the spray gun and the car with ________ charges. This means that the paint will be _____ to the car and little paint will be lost. Also, the paint will get onto parts of the car that are difficult to reach, making the coat more even.
opposite, attracted
When paramedics are trying to restart someone’s heart with a _____, they make sure that the paddles are _____ and that there is good _____ contact with the patient’s chest. When the _____ passes through the heart, it makes the heart contract and start beating again. It is important that the paramedics, or other people, do not receive a shock, so the handles of the paddles are _____.
.
defibrillator, charged, electrical, charge, insulated
.
How can you reduce the risk of shocks or damage due to the build-up of charge? Complete the sentences below.
One of the easiest methods is to connect to earth through a _____.
Anti-static liquids, sprays, and cloths contain something that _____ electricity.
Both aircraft and fuel trucks are connected to _____ before refuelling starts.
People working with electrical components use a wrist band containing a _____ connected to earth.
wire, conduct, Earth, wire
Electrostatics are used in paint spraying. Put the sentences in the correct order
to explain the process.
a) The spray is attracted to the negative object.
b) This is because the charged spray particles repel each other and spread out.
c) The particles form a thin, even paint layer on the object.
d) As the spray leaves the nozzle it becomes positively charged.
d, a, c, b
A cloth is rubbed over a balloon leaving the balloon negatively charged.
Which of the following statements are true?
a) The balloon lost positive charges.
b) There is an electric field around the balloon.
c) The cloth is now positively charged.
d) The cloth transferred negative charges to the balloon.
b, c, d
The charge transferred when a current of 5 A flows for 6 seconds is _____ C.
30
The charge transferred when a current of 4 A flows for 1 minute is _____ C.
240
The current flowing when 900 C is transferred in 10 minutes is _____ A.
3
The time taken for 400 C to be transferred by a current of 2 A is ______ s.
200
A lightning strike carries a current of 30 000 A and lasts for 0.5 ms.
Calculate the number of electrons flowing during the strike.
(The charge on 1 electron = 1.6 × 10−19 C)
9.4 × 10^19
