## Microsoft word - dc fundamentals trial mid-semester test.doc

D.C. Fundamentals Trial Mid-Semester Test
_____________________________________________________________________________________________

**DC ELECTRICAL FUNDAMENTALS **
** TRIAL MID-SEMESTER TEST **
** **

This test is

**closed** book, calculator permitted.

Answer questions in the spaces provided.

**60 MARKS TOTAL (70% pass)**
Clearly label all currents, resistors and voltage drops in the circuits and state any assumptions in
When calculating values, show clearly all steps, starting with the formula, then substituting with
numbers and finally show the measuring units of the obtained result. Otherwise

**NO MARKS** are

given

**Q1)** What does the ohmmeter measure?

**Q2)** What does the voltmeter measure?

**Q3)** What does the ammeter measure?

**Q4)** Define the term ‘resistor’.

**Q5)** Define the term ‘battery’.

**Q6)** How a voltmeter always should be connected? (circle the correct answer)

**[1 marks]**
a. in parallel b. in series c. doesn’t matter

**Q7)** How an ammeter always should be connected? (circle the correct answer)

a. in parallel b. in series c. doesn’t matter

**Q8)** How can twenty million Ohms be expressed in MΩ?

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D.C. Fundamentals Trial Mid-Semester Test
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**Q9)** How many μA is 0.0000123 A?

**Q10)** What is ‘electrical current’?

**Q11)** What is ‘voltage’?

**[2 marks]**
**Q12)** What does the abbreviation ‘e.m.f’. mean? What is the difference between ‘e.m.f.’ and

‘voltage’?

** **

**Q13)** Define the process of ‘measurement’.

**Q14)** What does ‘a base unit of measurement’ mean?

**Q15)** List the base units in the system SI.

**[3 marks]**
**Q16)** What does a ‘derivative unit of measurement’ mean?

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**Q17)** What are the main advantages of the system SI?

**[2 marks]**
**Q18)** What does ‘scientific notation’ mean?

**Q19)** What does ‘engineering notation’ mean?

**Q20)** Why are scientific and engineering notations being used?

**Q21)** Which of the two notations is more useful in electro technology?

**Q22)** Express these numbers in a scientific notation

**[4 marks]**
5000

0.000063

0.00000015

**Q23)** Express these numbers in an engineering notation

**[4 marks]**
7000

0.000047

0.00000058

**Q24)** Perform the following operations, using powers of ten

**[4 marks]**
(2 x 102) + (5 x 103) = (10 x 10-2) - (3 x 10-3) = (5 x 105) x (4 x 107) = (25 x 104) ÷ (5 x 10-3) =
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D.C. Fundamentals Trial Mid-Semester Test
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**Q25)** Express each quantity using a metric prefix

**[4 marks]**
**Q26)** Add these quantities

**[4 marks]**
**Q27)** What is an atom?

**Q28)** Draw a diagram of an atom according to the Bohr model. Clearly identify all the particles

**[2 marks]** **Q29)** What does the term ‘atomic number’ mean?

**Q30)** What is an ‘electron shell’?

**Q31)** Is it true that electrons at the L shell posses more energy than the ones in the K shell?

**[1 mark]** **Q32)** What are ‘valence electrons’?

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**Q33)** Define ‘conductors’.

**[1 marks]**
**Q34)** Define ‘insulators’.

**[1 marks]**
**Q35)** Define ‘semiconductors’.

**[1 marks]**
**Q36)** How many Coulombs does the number 123.1 x 1017 represent?

**[2 marks]**
**Q37)** The voltage in a circuit is 10 V. The el. charge is 500 mC. What is the energy?

**[2 marks]**
**Q38)** What two

*general* types of batteries do you know?

**[1 marks]**
**Q39)** What types of primary cells do you know?

**[1 marks]**
** **

Q40) What types of secondary cells do you know?

**[1 marks]**
**Q41)** What are the advantages of the lead-acid batteries?

**[1 marks]**
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**Q42)** What are the advantages of the lithium-ion batteries?

**[1 marks]**
**Q43)** How long time it takes to transfer 2 C of el. charge with an el. current of 200 μA?

**[2 marks]**
**Q44)** What is ‘memory effect’?

**[1 marks]**
**Q45)** What is the difference between a potentiometer and a rheostat?

**[1 marks]**
**Q46)** What is the resistance value and the tolerance of a resistor marked with red, violet, orange,

gold?

**[1 marks]**
**Q47)** Calculate the upper and the lower limit for the resistor value given above

**[3 marks]**
**Q48)** What are the main advantages of electronic switches as opposed to mechanical?

**[1 marks]**
**Q49)** What is the difference between a fuse and a circuit breaker?

**[1 marks]**
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D.C. Fundamentals Trial Mid-Semester Test
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**Q50)** Find the resistance of a 100 m copper wire, with a cross-sectional area of 1 mm 2 . The

resistivity of copper is ρ (Cu) = 1.75 x 10 8

**[3 marks]**
**Q51)** In the circuit below calculate the value of the current.

**[3 marks]**
** **

Q52) For the circuit in the previous question Q12 what resistor power values you would use?

** [3 marks] **
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D.C. Fundamentals Trial Mid-Semester Test
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**Q53)** What is the cost of the consumed electrical energy, if a heater with a power rating of 2500 W

is switched on for 10 hours? Use the domestic supply tariff for Western Australia, which in July

2012 was 24.8866 cents/kWh. Disregard the daily supply charges.

**Q54)** Given the following circuit calculate the total resistance.

**[3 marks]**
**Q55)** Given the following circuit calculate the total resistance.

**[3 marks]**
**Q56)** Calculate the power rating of the resistors from Q55 above assuming a power supply of 10V.

**[3 marks]**
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D.C. Fundamentals Trial Mid-Semester Test
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**Q57)** Calculate the following circuit using three different methods of calculation. By achieving the

same result three times you can be certain in its correctness. Also, in such a way you demonstrate

that you can correct your mistakes independently, without the need of a tutor.

**[6 marks]**
**Q58)** The input power of a machine is 150 W. The efficiency of the machine is 75 %. What is the

output

**[2 marks]**
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D.C. Fundamentals Trial Mid-Semester Test
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**Q59)** Calculate the following circuit using three different methods of calculation. By achieving the

same result three times you can be certain in its correctness. Also in such a way you demonstrate

that you can correct your mistakes independently, without the need of a tutor.

**[6 marks]**
**END OF TEST **
**(Check your work!)**
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Source: http://www.lubomir.name/engineering/DC_Fundamentals_Trial_Mid-Semester_Test.pdf

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