P3.1 Static Electricity

Question 1

Define: ampere (A)

Answer 1

the unit of current

Question 2

Define: battery

Answer 2

one or more cells

Question 3

Define: cell (electricity)

Answer 3

a device that produces a potential difference (separation of charge) from chemical reactions; what people normally call a ‘battery’

Question 4

Define: conventional current

Answer 4

the model where current flows from positive to negative, opposite to electron flow

Question 5

Define: coulomb (C)

Answer 5

the unit of charge

Question 6

Define: current (electric)

Answer 6

the rate of flow of charged particles (usually electrons), current = charge/time

Question 7

Define: electric charge

Answer 7

a property (like mass) of a particle; it can be positive or negative

Question 8

Define: electric field

Answer 8

a region produced by charged particles or objects where charged particles of objects experience a force

Question 9

Define: milliamp (mA)

Answer 9

1 milliamp = 1/1000 amp

Question 10

Define: spark

Answer 10

the breakdown of air that discharges a charged object; the heating of the air produces light and sound

Question 11

Define: static electricity

Answer 11

the charge that insulating objects acquire because of the transfer of electrons

Question 12

A material has to be this if it is to become charged when you rub it

Answer 12

insulator

Question 13

Objects become charged when these things are transferred.

Answer 13

electrons

Question 14

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

Answer 14

a) 1, 4, 5, 8

b) 2, 3 6, 7,

Question 15

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.

Answer 15

a, c, d

Question 16

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.

Answer 16

a, b , c

Question 17

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.

Answer 17

a, c, d

Question 18

_____ 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.

Answer 18

dust, charged, attracted

Question 19

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.

Answer 19

opposite, attracted

Question 20

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 _____.
.

Answer 20

defibrillator, charged, electrical, charge, insulated

.

Question 21

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.

Answer 21

wire, conduct, Earth, wire

Question 22

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.

Answer 22

d, a, c, b

Question 23

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.

Answer 23

b, c, d

Question 24

The charge transferred when a current of 5 A flows for 6 seconds is _____ C.

Answer 24

30

Question 25

The charge transferred when a current of 4 A flows for 1 minute is _____ C.

Answer 25

240

Question 26

The current flowing when 900 C is transferred in 10 minutes is _____ A.

Answer 26

3

Question 27

The time taken for 400 C to be transferred by a current of 2 A is ______ s.

Answer 27

200

Question 28

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)

Answer 28

9.4 × 10^19