Unit 9I (Energy and Electricity)

Question No. 1(05) 6 2(05) 6 3(97) 6 4(01) 6

Level 6 6 5 5 3 5 5 6 5 5 4 7

Mark

5(95) 6 6(03) 6 7(03) 6 8(01) 7 9(99) 7

10(05) 7 11(97) 7 12(01) 8

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Unit 9I (Energy and Electricity) 1. Alex makes an electromagnet. She winds insulated wire around an iron nail. She connects the wire to a power supply. She uses the electromagnet to pick up some steel paper-clips.

This is her prediction. The more turns of wire around the iron nail the stronger the electromagnet becomes. (a) (i) Give the one factor she should change as she investigates her prediction. ...................................................................................................................... ......................................................................................................................1 mark

(ii)

Give one factor she should keep the same. ...................................................................................................................... ......................................................................................................................1 mark

(iii)

Describe how she could use the paper-clips to measure the strength of the electromagnet. ...................................................................................................................... ......................................................................................................................1 mark

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Unit 9I (Energy and Electricity) (b) Alex wrote a report of her investigation.

What would an odd result suggest? ............................................................................................................................... ...............................................................................................................................1 mark

(c)

(i)

Which size paper-clips would Alex use to make her results more accurate? Tick the correct box.

1 mark

(ii)

Give a reason for your choice. ...................................................................................................................... ...................................................................................................................... ......................................................................................................................1 mark maximum 6 marks

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Unit 9I (Energy and Electricity) 2. The drawing below shows a garden water feature. It is solar-powered.

The solar cell absorbs energy from the Sun. The solar cell is connected to a motor in the bowl. The motor drives a pump. Water is pumped up to the jug and it flows back down to the bowl. (a) Use the information above to help you to complete the following sentences. Choose words from the list. c h e m g r a v i t a t i o n a l i c a l e l e c t r i c a l p o t e n t i a l k i n e t i c

l i g h t (i)

s o u n d

t h e r m

a l

The useful energy change in the solar cell is from light to .................................... energy.1 mark

(ii)

The useful energy change in the motor is from electrical energy to .................................... energy.1 mark

(iii)

As the water flows from the jug to the bowl ....................................... energy is changed into .................................... energy.2 marks

(b)

Give one advantage and one disadvantage of using a solar cell to power the water feature. advantage .................................................................................................... ......................................................................................................................1 mark

disadvantage ................................................................................................ ......................................................................................................................1 mark Rainford High Technology College 4

Unit 9I (Energy and Electricity)maximum 6 marks

3.

(a)

A torch battery is an energy resource. How is the energy stored in a torch battery? Tick the correct box. as chemical energy

as kinetic energy

as potential energy

as thermal energy1 mark

(b)

When a torch is switched on, energy is transferred from the battery to the bulb. How is energy transferred from the battery to the bulb? Tick the correct box. by electricity

by light

by sound

by thermal energy1 mark

(c)

Energy is transferred from the torch bulb to the surroundings. Choose from the following terms to complete the sentences. electricity (i) light sound thermal transfer

Energy is transferred from the torch bulb to the surroundings in a useful way by ...............................................1 mark

(ii)

Some energy is wasted. The wasted energy is transferred from the bulb to the surroundings by ...............................................Rainford High Technology College 5

Unit 9I (Energy and Electricity)1 mark

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Unit 9I (Energy and Electricity) (d) The torch is lifted up and put on a high shelf.

Energy is transferred to the torch as it is lifted up. The energy is stored in the torch while it stays on the shelf. What energy has the torch gained? ....................................................................................................................1 mark Maximum 5 marks

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Unit 9I (Energy and Electricity)

4.

The drawings show a weightlifter. The stages in weightlifting are labelled A, B, C, D and E. lift e d f a llin g p r e p a r in g lift in g h itt in g flo o r

A (a) (i)

B

C

D

E

Complete the sentences below. As the weights were lifted up, energy was transferred from the man to the weights. This energy had been stored as energy in the of the mans arms.2 marks

(ii)

How was energy stored in the weights at stage C? Tick the correct box.

as chemical energy as kinetic energy

as elastic energy as gravitational potential energy1 mark

(b)

Complete the sentences below. (i) In stage D, as the weights were falling, the energy was transferred from energy to energy.1 mark

(ii)

In stage E, as the weights hit the floor, the energy was transferred from energy to energy.1 mark Maximum 5 marks

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Unit 9I (Energy and Electricity)

5.

A bookshelf is 1 metre above the floor. As a book falls from the shelf to the floor it loses 7.5 J of potential energy. (a) (i) Tick the box by the correct statement about the kinetic energy of the book.

W h ile t h e b o o k w a s r e s t in g o n th e s h e lf it h a d 7 . 5 J o f k in e tic e n e r g y . W h ile t h e b o o k w a s fa llin g , it s p o t e n t ia l e n e r g y w a s b e in g tr a n s f o r m e d in to k in e tic e n e r g y . W h ile t h e b o o k w a s fa llin g , it s k in e tic e n e r g y r e m a in e d c o n s t a n t. W h ile t h e b o o k w a s fa llin g , it lo s t k in e tic e n e r g y .1 mark

(ii)

How much kinetic energy does the book have just before it hits the floor? .......................................................................................................... J1 mark

(b)

When the book hits the floor it stops and loses all its kinetic energy. What happens to this energy? ..................................................................................................................... .....................................................................................................................1 mark Maximum 3 marks

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Unit 9I (Energy and Electricity)

6.

(a)

Jacquie has a mobile phone. Energy is stored in the battery of the phone. The drawing shows the battery being charged.

(i)

Which energy transfer takes place in the battery as it is being charged? Tick the correct box. chemical to sound electrical to chemical sound to thermal thermal to electrical1 mark

(ii)

When the battery is fully charged, Jacquie unplugs the phone. Which energy transfers take place when the mobile phone rings? Tick the correct box. chemical to electrical to sound electrical to chemical to sound kinetic to electrical to sound thermal to electrical to sound

1 mark

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Unit 9I (Energy and Electricity) (b) Jacquie can change the ring-tone of her phone. The diagrams below show the patterns made by four sound waves on an oscilloscope screen. They are all drawn to the same scale.

Write the letter of the sound wave that matches each of the descriptions below. (i) (ii) (iii) a loud sound with a low pitch .................

a quiet sound with a high pitch ................. a loud sound with a high pitch .................3 marks Maximum 5 marks

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Unit 9I (Energy and Electricity) 7. Peter measured the current through each of three similar bulbs in a parallel circuit.

A1 A2 A3He had only one ammeter and he placed it first at A1, then A2, then A3, in order to measure the currents. The table shows his results. position of ammeter A1 A2 A3 current, in amps 0.14 0.16 0.15

(a)

He expected the current readings to be the same for each bulb but found they were different. Suggest two reasons why the readings were different. 1. ................................................................................................................ 2. ................................................................................................................2 marks

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Unit 9I (Energy and Electricity) (b) Peter then measured the current at A4 and recorded it as 0.45 A. He concluded that the current at A4 could be calculated by adding together the currents through each of the bulbs at positions A1, A2 and A3.

A4

He added two more similar bulbs to his circuit, in parallel. The current through each bulb was 0.15 A. Use Peter's conclusion to predict the current at A4 with the 5 bulbs in the circuit. ................ A A4

1 mark

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Unit 9I (Energy and Electricity)

(c)

Peter left the circuit connected overnight. He used a datalogger to measure the current at position A4 at regular intervals of time. The next morning the bulbs were dim. Using the axes below, sketch (do not plot) how the current at position A4 might change with time. Indicate on the graph: (i) (ii) The correct labels for each axis, including the correct units. The shape of the graph you would expect to obtain.

0

02 marks Maximum 5 marks

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Unit 9I (Energy and Electricity)

8.

(a)

A pupil makes a small coil of copper wire and passes an electric current through it. The pupil places a small magnet near the coil.

c o il

N

S

m agnet

The magnet is attracted towards the coil. The pupil turns the magnet around so that the South pole is nearest the coil. What effect, if any, will this have? . .1 mark

(b)

The pupil uses the coil and the magnet to make a simple ammeter to measure the current through a bulb.

s c a le

s tra w p iv o t m agnet

p a p e r c lip

c o il

not to scaleRainford High Technology College 15

Unit 9I (Energy and Electricity)

(i)

The paper clip is used to balance the weight of the magnet. Why is the paper clip further away from the pivot than the magnet is? 1 mark

(ii)

Explain how a current in the coil makes the straw pointer move. 2 marks

(iii)

The pupil places a piece of soft iron in the middle of the coil. Describe and explain how this will affect the reading on the scale when the same current flows through the coil. 2 marks Maximum 6 marks

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Unit 9I (Energy and Electricity)

9.

A flywheel is a rotating wheel which is used to store energy.

(a)

Energy must be transferred to a flywheel to make it rotate. How is the energy in the rotating flywheel classified? Tick the correct box. as chemical energy as kinetic energy as potential energy as thermal energy1 mark

(b)

A flywheel is rotating at a high speed. No energy is being supplied to it. The flywheel is used to turn a dynamo, and the energy from the dynamo is used to light a bulb. (i) The bulb is left connected until the flywheel stops rotating. Not all the energy stored in the flywheel is transferred to the bulb. Some of it is lost. Give two places from which it is lost, and explain how it is lost. 1. ........................................................................................................... ................................................................................................................. 2. ........................................................................................................... .................................................................................................................2 marks

(ii)

The experiment is repeated using a different bulb which gives out more energy each second. Compared to the first light bulb, describe how the second light bulb will affect the motion of the flywheel, and explain your answer. ................................................................................................................. ................................................................................................................. ................................................................................................................. .................................................................................................................Rainford High Technology College 17

Unit 9I (Energy and Electricity)2 marks Maximum 5 marks

10.

John used an electrical heater to heat a cup of water. He kept stirring the water. When the temperature reached 20C, he started his stopwatch and measured the temperature of the water every half minute.

He switched off the heater after 4 minutes, but continued to record the temperature. His results are shown in the table. One measurement is missing and another appears to be wrong. Time (minutes) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 57 56 58 59 59 Temperature (C) 20 26 31 36 41 46

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Unit 9I (Energy and Electricity)

(a)

Use the results in the table to draw a graph on the grid. Label the axes. Plot the points and draw a smooth curve of best fit.

(

)

(4 marks

)

(b)

From your curve, estimate the temperature of the water after three minutes. ............C1 mark maximum 5 marks

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Unit 9I (Energy and Electricity)

11.

a t in y w h ite h o t s p a r k fr o m a s p a r k le r

a h e a v y ir o n p o k e r, h o t e n o u g h t o g iv e o u t a d u ll r e d g lo w

a fr e s h ly b o ile d e g g

a g la s s o f c o ld w a te r in a fr id g e

(a)

Each of the four objects shown above started at room temperature. Now they are all at different temperatures, as described by the labels. (i) Which object is at the highest temperature? ..........................................................................................................1 mark

(ii)

Which object has lost thermal energy? ..........................................................................................................1 mark

(iii)

Which object has had the largest gain in thermal energy? ..........................................................................................................1 mark

(b)

Omar puts a hot steel ball into a beaker of cold water. He waits until the temperatures of the ball and the water are the same. From his results, he calculates that: the thermal energy stored in the steel ball has fallen by 3770 J; the thermal energy stored in the water has risen by 2940 J. The energy stored in the water rose by less than 3770 J. What has happened to the other 830 J? .................................................................................................................... ....................................................................................................................1 mark Maximum 4 marks Rainford High Technology College 20

Unit 9I (Energy and Electricity)

12.

Anita has arranged a horseshoe magnet with a long bar magnet pivoted above it. p iv o t N N S h o rs e s h o e m agnet S bar m agnet

(a)

Whenever Anita tips the bar magnet, it always moves back to the position shown in the diagram. Explain why this happens. . . . .2 marks

(b)

When a current is passed through a coil, it produces magnetic poles as shown in the diagram below.

N

S

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Unit 9I (Energy and Electricity)

Anita winds a coil around each end of the horseshoe magnet as shown below.

p iv o t N N S S bar m agnet

h o rs e s h o e m agnet(i) Describe what will happen to the bar magnet when she closes the switch. Explain your answer. 3 marks

(ii)

Anita reverses the battery. Suggest what happens to the bar magnet. 1 mark

(iii)

Anita replaces the battery with a power supply which changes the direction of the current every second. Suggest what happens to the bar magnet. 1 mark Maximum 7 marks

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Unit 9I (Energy and Electricity)

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