Questions on Energy in Circuits

r--I~Now read the paragraph about this circuit and fill in thegaps using the words in the grey box.

brighterlamp cells

incompleteheat

seriesoff light

two increased currentuseful electrical wires

_____ lights up. The 3V battery is made up of 1.5V

_____ connected in ,. The energy is transferred along

_____ to the lamp. The lamp changes energy to _

If the battery voltage is to 6V, the lamp glows and more

Q2 Electricity can easily be changed into other types of energy.

Match up the device with the useful form of energy that it produces from electricity.

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Q3 This question is a number of statements about electrical energy. All you haveto do is to choose the right choice from the brackets and put a ring around it.

a) Electrical energy flows around a circuit as an electric (current / direction).

b) An electrical current is a flow of (atoms / charge).

c) When electric charge flows through a resistor, energy is transferred as (heat / sound).

d) We measure the amount of energy transferred in units called (amperes / joules).

e) The transfer of 1 joule of energy in a time of 1 second means the power is 1 (watt / olt).

Section One - Electricity and Ma

Questions on Energy in CircuitsQ4 Electrical power can be found in two different ways, depending

on what information you are given. Written below are the twoequations and formula triangles to work out electrical power.

Power (W) = Potential Difference (V) x Current (A)

•Power (W) = Energy (J) / Time (s)••

Now fill in the table below. You will need to use the first equation to complete the Currentand Power columns, and the second equation for the Energy column.

Potential difference Current Power Time Energy(V) (A) (W) (s) (J)

3 0 8

12 24 3

12 48 96240 2400 10

Q5 This diagram shows a heating coil connected to a battery in aheating experiment. Readings are taken of the temperatureevery minute. The results are shown in the table below.

Time (minutes) 0 1 2 3 4 5 6 7 8Temperature rC} 20 40 58 71 82 89 95 100 100

a) Use the results from the table to draw a graph of temperature against time on the graphpaper below.

TemperatureeC)

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! -I

-+

H- I ! +- I-.<-

!- - - - - -- ._-

II I I ! I

,I !-I i ! j

I I! I I

j I , i - I L 1-! I I

, ! I I

I ! , j -j-~ I -+I I i--r- -'- -+-, I

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c) What is the highest temperature that the experiment will get to? .

Dues. I estic Eledricit)!

joules present units current take twice energy

The cost of electricity depends on the number of that are used.

Previous Reading

Present Reading....-.-.:~-57413

a) Use a calculator to work out the number of units of electricity each house has used.Write your answers in the boxes beneath the dials.

b) Who has used the most electricity? .

Kilojoule-hour

b) Listed below are 4 definitions of a unit of electricity. Tick the one correct definition.

It is when an energy of 1000 joules is used in 1 second. c:=JIt is when a power of one watt is used for 1 second. c:=JIt is when a power of 1000 W (1kW) is used for I hour. c:=JIt is when an energy of 1 joule is used in 1 hour. c:=J

Section One - Electricity and Ma

auestions on the Cost of Eledricit)!.

Q4 Changing between watts and kilowatts needs to be done orne e.

a) liow many watts are there in 1 kilowatt? .

Q5 Listed below are a number of different units. Decide which are units of energy andwhich are units of power, then write them down in the correct column in the table below.

Power Energy

Megawatt kW

joules

watts kilojoules

W kilowatt-hour

units kWh

kilowatt MW

Q6 This question is on working out the cost of usingdifferent appliances for different lengths of time.

Complete the table below given that the cost of electricity is lOp per unit. Use the

following equation - I Cost of Electricity = Units used x cost per unit IThe first example is done for you.

Appliance Power Time Units usedI

Cost of ElectricityRating (kW) (h) at lOp per unit

Storage Heaters 2 4 2x4=8 8 x 10 = 80p

Cooker 7 2

I-bar Electric Fire 1 1.5

Kettle 2 0.1

Iron 1 1.2

Refridgerator 0.12 24.0

Lamp 0.06 6.0Ra . Cassette 0.012 2.0

Ouestions on Mains ElectricityL

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I :J;j1__ 11_-

WORD LIST national grid

I Electrical Word I

a) Transmit

b)ACc) DCd) Turbine

e) Power station

f) Transformer

g) Fuse

h) Circuit breaker

I rotary motor driven by steam II place for generating and distributing electricity II direct current II send from place to place II changes the voltage of alternating current II alternating current II resettable device for cutting off electrical current II a thin wire that melts when the current is too high I

Q3 Complete the gaps in the following paragraph about electricity generationusing the words from the WORD LIST.

electromagnetgenerator coal

oil chemical natural gasnuclear turbine

Section One - Electricity and