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I have typed these out (scanner is broken  ) for the C&G 2330 level 2.

Exercise 1. Unit 2: Outcome2: Session 1

1/. Give a definition of current, in your own words.

2/. What is a free and what is a bonded electron?

3/. What is the quantity of electricity measured in?

4/. If 3 A flows in a circuit for 2 hours, what will be the charge?

5/. For a charge of 900 C and a current of 2 A, what will b the time in minutes?

6/. The time taken for a battery to charge is 4 hours, what will be the charge if a current of 4 A flows?

7/. How many electrons can inhabit the innermost shell of an atom and what label is attached to that shell?

8/. What is an ion?

9/. In what direction does conventional current flow?

10/. In which direction do electrons flow?

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Exercise 2.1

1/. Give three effects of an electric current.

2/. Give two suitable examples of ach of the effects stated in (1).

3/. Give two examples of a cell.

4/. What is an electrolyte?

5/. Give two types of secondary cell.

6/. When would you use a thermocouple?

7/. What is a combination of cells called?

8/. What happens whencurrent passes through an electrolyte?

Electrician Forum 2008 (www.electricianforum.co.uk)

 
Exercise 5 Unit 2: Outcome 5

1/. What remains constant in a series circuit?

2/. What remains constant in a parallel circuit?

3/. If three lamps were connected in series and each had the same resistance, what would be the voltage dropped across each one if the supply voltage was 230 V?

5/. Three resisters of 4 Ω, 16 Ω and 24 Ω are connected in parallel. If the supply voltage is 110 V, what will be the:

i/. total resistance:

ii/. current in each leg of the circuit:

iii/. total current:

6/. Four resisters are connected in a series/parallel circuit. The 6 Ω and 12 Ω resistors are connected in parallel with each other and are then connected in series with the 17 Ω and 27 Ω resistors that are also connected in parallel with each other. If the supply voltage is 230 V, calculate:

i/. Total resistance:

ii/. Total current:

iii/. Voltage dropped across each network:

iv/. Current in each leg of the networks:

7/. A cell has a terminal voltage of 1.95 V when supplying a current of 8.2 A. The terminal voltage rises to 2.1 V when the load is switched off. What is the internal resistance of the cell?

8/. Two resistors of 5 Ω and 10 Ω are connected in parallel across a battery. The e.m.f of the battery is 24V and the internal resistance is 1.2 Ω. Determine the total current in the circuit and terminal voltage of the battery. What will be the voltage dropped across the two parallel resistors?

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Exercise 2.

1/. A motor is being carried along a rail. With what Force does the motor of mass 350 kg hit the ground when it falls?

2/. Describe the difference between a scalar and a vector quantity.

3/. What forceis required to hold up an object of mass 20 kg?

4/. A car has mass of 1.5tonnes travelling at 20 ms-1 is brought to a halt by a tree in 1 s. What force is exerted on the tree?

Exercise 7. Unit 2: Outcome 2: Session 7

1/. Define magnetic flux density, and then state it in your own words.

2/. Draw the pattern you would expect to see when two permanent magnets are brought close together when:

a/. Like poles are together (repulsion):

b/. Unlike poles are together (attraction):

3/. The flux in the pole of an electric motor is 15 mWb. If the area of the pole is 18 x 10

 
Exercise 8. Unit 2: Outcome 2: Session 8

1/. Name three factors that affect the size of the induces emf?

2/. If the induced emf in a coil is 220 V, it

 
Current

1/. A current of 5 A flows for a period of 2 minutes. How much charge is passing through the circuit?

2/. A charge of 12 C passes a point in a circuit in 0.3 s. What is the current in the circuit?

Magnetic Flux.

1/. A magnetic field of 7.5 mWb exists in an iron core, which has an area of 2 x 10

 
Excercise 7 Unit 2: Outcome 2: Session 7

1/. Define magnetic flux density, and then state it, in your own words.

2/. Draw the pattern you would expect to see when two permanent magnets are brought close together wen:

a/. Like poles are together (repulsion).

b/. Unlike poles are together (attraction).

3/. The flux in the pole of an electric motor is 15mWb. If the area of the pole is 18 x 10

 
Exercise 8

1/. Name three factors that affect the size of the induced emf?

2/. If the induced e.m.f in a coil is 220 V, it's length per turn is 75 mm and it has 700 turns, what will be its velocity within the magnetic field if its magnetic flux density is 0.35 T?

3/. What two rules can be used to determine the direction of the induced e.m.f?

4/. A conductor is moved through through a magnetic field of strength 380 mT. If there are 850 turns and the diameter of the former that the coil is wound is150 mm. What will be the force applied to the conductor when it has a current of 0.25 A flowing in it?

5/. What is the difference between self and mutual induction, and give an example of each?

6/. An electromagnet has an inductance of 14 H. If the current in the coil falls from 2.5 A to 1.1 A in 10 ms, what will be the average induced emf?

7/. The current in an air-cored coil increases from 0.5 A to 25 A in 0.25 s. If the inductance is 1.5 H, what will be the induced emf?

8/. The coil of an electric bell has an inductance of 2.1 H. Calculate the e.m.f induced in the coil when a current of 0.15 A is reduced to zero in 15 ms.

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POWER

1/. Calculate the current demanded by a 60 W, a 100 W, and a 15o W lamp when they are connected to a 230 V supply.

2/. The insulation resistance between two conductors is 0.5 MΩ. The p.d. between the two conductors is 200 V, what will be:

a). the leakage current

B). the power loss.

Transformer Ratios:

1/. A 400/230 V single-phase transformer has a primary current of 12 A. Determine the secondary current.

2/. A single-phase transformer reduces the voltage from 230 V to 6 V. If the secondary winding has 10 turns of wire on it and the primary has a current of 2.5 A, what will be:

i/. the number ot turns on the primary winding?

ii/. the current in the secondary?

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EXERCISE 10:

1/. Describe what happens when a magnet is moved towards a coil.

2/. What would happen if the magnet in Q.1, moved towards the coil faster?

3/. What do you call the current that is produced by the movement of a magnet relativeto a coil?

4/. Name the three parts of a transformer.

5/. A transformer has 200 turns on the primary and 480 turns on the secondary. If the required secondary voltage is 240 V, what is the supply voltage?

6/. If a transformer has a secondary current of 1 A, and primary and secondary voltages of 100 V and 24 V resectively, what will be it's primary current?

7/. A conductor 350 mm long, cuts a magnetic filed of flux density 0.8 T. What will be the induced emf when the conductor is travelling at 5 ms

 
a.c. and d.c. Supplies:

1/. What is the period if the frequency is 75 Hz?

2/. If the cycle is 7.6 ms. What will be the frequency?

3/. What maximum voltage do I need to achieve an ms voltage of 254 V? State the peak and the peak-to-peak voltage also.

4/. If I have a 440 V supply, what will be the maximum voltage? State also, the peak voltage and the peak-to-peak voltage.

5/. What two things is the value of inductance affected by?

6/. Give two examples of an inductor.

7/. State the symbol and the unit for the inductor.

8/. State the three common ways of producing d.c.

9/. Which two types of d.c. supply would you use to power a games console?

10/. What do you use to convert a d.c. generators' supply to true d.c?

11/. Why is a capacitor used in a bridge rectifier?

12/. Draw a full wave bridge rectifier.

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Three Phase

1/. Can you think of any reasons why it is necessary to spread our loads across three phases rather than making things simple with one phase?

Electrical Cable

1/. Give three examples of good conductors:

2/. Give three examples of good insulators:

3/. Give an example of a material that is neither a good conductor or a good insulator:

4/. Knowing what makes a good conductor, what could we say about the numer of electrons in the outer shell of an insulator?

Exercise 3. Unit 2: Outcome 3: Session 3

1/. An engineering workshop is being wired in pvc/swa/pvc. Why?

2/. A three-bedroomed house is to be rewired. What cables would you choose and why?

3/. Why would you use aluminium cables rather than copper?

4/. Give three advantages of MI cable.

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Exposed & Extraneous Conductive Parts:

1/. Give five exaples of what you would consider to be, exposed-conductive-parts.

2/. Give three examples of what you would consider not to be exposed-conductive-parts.

3/. Give five examples of what you woudl consider to be extraneous-conductive-parts.

4/. Give three examples of what you would consider not to be extraneous-conductive-parts.

_____________________________________________

Exercise 5: Unit 2: Outcome 3: Session 5

1/. Explain what the difference is, between exposed and extraneous-conductive-parts and give two examples of each.

2/. What are the differences between a main equipotential bonding conductor, a supplementary bonding conductor, a circuit protective conductor and an earthingconductor?

3/. Why is it important to create an equipotential zone within an electrical installation?

4/. Take a look around an electrical installation and name the various elements that would require earthing or bonding.

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Exercise 6. Unit 2: Outcome 3: Session 6

1/. State the two main means of providing protection against direct contact.

2/. What is the main way of providing protection against indirect contact?

3/. What is the relationship between providing protection against indirect contact and a protective device?

4/. What make a rewirable fuse a good choice when compared to an HRC fuse?

5/. Why might you choose to use a circuit breaker rather than a BS 3036 fuse?

6/. For the following numbers, state what type of device they are:

i). BS EN 60269

ii). BS 3036

iii). BS EN 60898

iv). BS 1362

V). BS 1361

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Exercise 4. Unit 2: Outcome 4: Session 4

1/. What checks would you make on a pair of wooden ladders?

2/. What is the ratio used when erecting a ladder?

3/. How far past a working platform, should a ladder extend?

4/. At what height does it become necessary to install toe boards?

5/. Whick set of Regulations cover the use of access equipment?

6/. What does SWL stand for?

7/. What are the two factors that affect where slings should be placed around a load?

8/. Whatis the first requirement before lifting any load?

9/. List how a load should be lifted from the floor.

10/. State three types of sling arrangement. List each of their advantages and disadvantages.

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