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### Transcript of Edexcel GCSE Science P1.5 Generation and Transmission of Electricity Test 12_13 DS

• PART A

PART A 1

Surname

Name

Year 4 Science

Semester 2

Test 4

Unit P1

Universal Physics

Topic 5 Electricity

Friday 19th

May 2013

Part A

Time: 20 minutes

FORMULAE

You may find the following formulae useful.

wave speed = frequency wavelength v = f

takentime

covered distancespeed wave

t

xv

electrical power = current potential difference P = I V

cost of electricity = power time cost of 1 kilowatt-hour

takentime

usedenergy power

t

EP

%100device) the tosuppliedenergy (total

device) by the nsferredenergy tra (usefulefficiency

coilsecondary on turnsofnumber

coilprimary on turnsofnumber

voltagesecondary

ltageprimary vo

s

p

s

p

N

N

V

V

• PART A

PART A 2

1. (a) Put a cross ( ) in the box next to the correct answer.

[1 mark]

Voltage is

A the energy

B the rate of flow of charge

C the energy per coulomb

D the rate of flow of energy

(b) Below we see a graph of the energy provided to different amounts of charge by a photovoltaic

cell working in bright light.

(i) Describe one disadvantage of using solar cells.

[1 mark]

(ii) Use the graph to show that the voltage provided by the solar cell is 0.6V.

[2 marks]

Voltage = V

(iii) The solar cell provides an average current of 1.5 A.

Use your answer in (ii) to calculate the power produced by the solar cell.

Dont forget the unit.

[2 marks]

Power =

0

1

2

3

0 2 4 6

Energy

(Joules)

Charge (Coulombs)

a photovoltaic cell

• PART A

PART A 3

(iv) How much energy would the solar cell give in 1 minute?

[2 marks]

Energy = J

A solar cell generates direct current.

(v) Describe the difference between direct current and alternating current.

[2 marks]

(vi) State why a transformer cannot be used to increase this voltage.

[1 mark]

(c) The table shows some information about the wind-powered generator.

cost (including installation) 2500

electrical energy produced in one year 900 kWh

Electricity from the National Grid costs 15 p per kWh.

Calculate the payback time for the wind-powered generator.

[3 marks]

payback time = .............................................................................. years

[Total for Q1 = 14 marks]

_______________________________________________________________________________________

• PART A

PART A 4

2. Some students carry out investigations with an electric motor.

(a) The students read the statement: All the energy supplied to the motor eventually ends up as

thermal energy in the surroundings.

This statement best describes the idea of

[1 mark]

A renewable energy

B energy efficiency

C sustainable energy sources

D conservation of energy

(b) The students use the electric motor to lift a weight.

The diagram represents the energy transfers in the electric motor.

(i) How much energy is wasted?

[1 mark]

wasted energy = .................................................................... J

• PART A

PART A 5

(ii) Calculate the efficiency of the motor.

[2 marks]

efficiency = .......................................................................

(c) The case of the motor is painted black.

Give a scientific reason why the case of the motor is painted black. [2 marks]

[Total for Q2 = 6 marks]

_______________________________________________________________________________________

TOTAL FOR PART A = 20 MARKS

END

• PART B

PART B

Surname

Name

Year 4 Science

Semester 2

Test 4

Unit P1

Universal Physics

Topic 5 Electricity

Friday 19th

May 2013

Part B

Time: 20 minutes

FORMULAE

You may find the following formulae useful.

wave speed = frequency wavelength v = f

takentime

covered distancespeed wave

t

xv

electrical power = current potential difference P = I V

cost of electricity = power time cost of 1 kilowatt-hour

takentime

usedenergy power

t

EP

%100device) the tosuppliedenergy (total

device) by the nsferredenergy tra (usefulefficiency

coilsecondary on turnsofnumber

coilprimary on turnsofnumber

voltagesecondary

ltageprimary vo

s

p

s

p

N

N

V

V

• PART B

PART B

1. (a) Scientists say that graph 1 shows an alternating current while graph 2 shows a direct current.

The two graphs differ in several ways.

State the difference between the currents which makes one alternating and the other direct.

[1 mark]

(b) A transformer is 100% efficient.

It has 200 turns on the primary coil and 3000 turns on the secondary coil. The input voltage is

55 V.

(i) Show that the output voltage is about 800 V.

[3 marks]

• PART B

PART B

(ii) Calculate the current in the secondary coil when the current in the primary coil is 0.50 A.

[2 marks]

current in secondary coil =............................... A

*(c) The diagram shows how electricity produced at a power station is transmitted to distant houses.

By using transformers, energy losses in the transmission lines are reduced. Explain how this reduction is achieved, even though some energy is wasted in the transformers

themselves. [4 marks]

• PART B

PART B

(d) When an electric current flows through a transmission cable, a magnetic field is produced. The graph shows how the strength of the magnetic field varies with distance from both

overhead and underground transmission cables that carry the same current.

(i) What conclusions may be drawn from this graph?

[2 marks]

• PART B

PART B

(ii) Some people think that, because of the magnetic fields, living close to transmission cables is

dangerous to health. Laboratory studies on mice and rats exposed to magnetic fields for two or

more years found that the magnetic fields had no effect on the animals health.

Draw a ring around the correct answer in the box to complete the sentence.

[1 mark]

[Total for Q1 = 13 marks]

_______________________________________________________________________________________

2. The pie charts show the relative proportions of electricity generated in Japan from different energy

sources in 1975 and 2005.

(a) Describe and suggest a reason for the differences in the energy sources used in 2005

compared with 1975.

[1 mark]

• PART B

PART B

(b) (i) A newspaper reported a scientist as saying:

What has been stated in the newspaper?

a fact a guess a prediction

[2 marks]

...

...

[Total for Q2 = 3 marks]

_______________________________________________________________________________________

3. A farmer has installed a biogas electricity generator on his farm. This device generates

electricity by burning the methane gas produced from rotting animal waste. Methane is

a greenhouse gas. When methane burns, carbon dioxide and water are produced.

The animal waste rots in an anaerobic digester. The digester and the generator are

kept inside a farm building and cannot be seen from the outside.

(a) The animal waste used in the anaerobic digester is a renewable energy source.

What is meant by an energy source being renewable?

[1 mark]

...

...

(b) Suggest one reason why farmers have been encouraged to install their own biogas

generators.

[1 mark]

...

...

• PART B

PART B

(c) It would have been cheaper for the farmer to have bought and installed a small wind

turbine.

Give two advantages of using the biogas generator rather than a wind turbine, to

generate the electricity used on the farm.

[2 marks]

...

...