Quiz 4-2 Solution

Part 1: Fill in the Blanks and Definitions

n A _________________ is a useful device for making non-permanent electrical connections in order

to evaluate a concept. It consists of a series of holes aligned in rows across the entire surface of an

insulation material. Copper strips are run in parallel under the rows of holes and are used as

conductor pathways. breadboard

n More permanent than the above, a _____________________________________ is made from a

thin layer of conductor material, usually copper foil, cut in strips and attached to an insulated board.

The strips act as conductor paths. Components are inserte holes in the insulated board

and then soldered to the conductive strips at circular spots. printed circuit board

n The flow of electrons is called _____________________ current

n The charge of 6.14 x10¹⁸ electrons is called a ____________________ coulomb

n The unit of measurement for current is the __________________ ampere

n __________________ is the force that moves electrons in a circuit voltage

n __________________ is a general name for materials with high resistance Insulators

n __________________ is a general name for materials with low resistance conductors

n Write the symbol or letter for the following items in the space provided

n Electrical prefixes Some common prefixes used in electronics are shown in the table on the right. Write the symbol or letter for each of the symbols in the space provided	Prefix	Symbol or Letter
	10^-9	n
	10^-6	m
	10^-3	m
	10³	K
	10⁶	M
	10⁹	G

n One amp is the amount of current that flows in a conductor when one ____________ of charge

moves past a point in one second. coulomb

n What is the name of the single instrument used to measure

Ø Resistance: ________________________________ Ohmmeter

Ø Current: ___________________________________ Ammeter

Ø Voltage: ___________________________________ Voltmeter

n A resistor's ______________________ is the amount that it may vary and still be acceptable.

tolerance

n For each of the following, indicate whether the instrument is connected in series with the item being

measure or in parallel (your answer should be either series or parallel).

Ø Resistance: _________________ Parallel Ø Current: ____________________ Series

Ø Voltage: ____________________ Parallel

n List the 2 primary types of ground discussed in the text.

Ø _________________________Earth Ø ________________________________ Electrical

n The type of ground used in a car is referred to as a ________________ ground chassis or

electrical

n Variable resistors used to control resistance are called ________________ potentiometers

n Variable resistors used to control current are called _________________ rheostats

n The relationship of current, voltage, and resistance is given by _______________ law. Ohm's

n Current that flows in one direction and then the other is called ___________________ AC

n Current that flows in one direction only is called ___________________________ direct current.

n The basic unit of power is the ____________________________ watt

n The _________________ is a device used to control a large flow of current by means of a low

voltage, low current circuit. relay

n A __________________ is a device used to transfer energy from one circuit to another using

electromagnetic induction. transformer

n The opposition to alternating current as a result of inductance or capacitance is called

_________________ reactance.

n Induced emf in any circuit is always in such a direction as to oppose the effect that produces it.

This is a statement of ________________ law. Lenz's

n _____________________ is an inherent property of an electrical circuit that opposes a change in

current. Inductance

n The total resistance to the flow of an alternating current as a result of resistance and reactance is

called _________________________ impedance

n A __________________ is a device that temporarily stores an electric charge. capacitor

n An __________________ is an electronic component that is used to produce inductance in a

circuit. A coil is an example of such a component. inductor

n Ohm's law is valid for AC circuits, except that _________________ must be substituted by

resistance. impedance

n The _______________ __________________ is the time period required for the voltage of a

capacitor in an RC circuit to increase to 63.2% of maximum value or decrease to 36.7% of

maximum value. time constant

n The formula for capacitive reactance is X_C = 1/2PfC. Provide the units for each of the components

of this formula listed below.

Ø X_C: ____________ohms Ø f: _________________hertz Ø C: ________________farads

n The following formula was discussed in chapter 15. Z = (R² + X_C²)^1/2

Ø Z is referred to as ________________________ impedance

Ø The units of Z are ___________ohms Ø The units of R are ___________________ ohms

n In a step down transformer, the higher current will be on the ________________

while the lower current will be on the ________________ side. primary secondary

n Most transformer calculations are based on the assumption that transformers are

100% efficient. What are the 3 types of transformer losses.

Ø ________________________________________copper loss

Ø ________________________________________eddy current

Ø ________________________________________hysteresis

n The ______________________ of AC current or voltage produces the same results as the

equivalent DC voltage or current. effective value

n Check the appropriate answer below

Ø To increase the total voltage, batteries are placed in ___ series ____ parallel series

Ø To increase the total current, batteries are placed in ___ series ____ parallel parallel

Part 2: Circuit Analysis- DC and Resistance

n Given a circuit with a DC power of 9 volts supply and 3 resistors in series. Each resistor has a

value of 1 ohms.

Ø What is the total or equivalent resistance in this circuit?

R1 + R2 + R3 = 3

Ø What is the voltage drop across each resistor?

The voltage drop is proportional to the resistance and they sum to the total source.

Voltage drop across each resistor is 3 volts

n Given a circuit with a DC power supply, supplying 9 volts and 4 resistors in parallel. Each resistor

has a value of 2 ohms.

Ø What is the total or equivalent resistance in this circuit?

1/RT = 1/2 + 1/2 + 1/2 + 1/2 = 2 gives R_T = 2

Ø What is the voltage drop across each resistor?

9 volts

n Given a circuit with a resistor rated at 2 ohms and 2 DC batteries, connected in series, each rated

at 12 volts. What is the total voltage in the circuit?

24 volts

n Given a circuit with a resistor rated at 2 ohms and 2 DC batteries, connected in parallel, each rated

at 8 volts. What is the total voltage in the circuit?

8 volts

n How much current is used by a 240-watt, 120 volt light bulb?

P = IE

240= I(120) gives I = 240/120 = 2 amp

n Clearly state Kirchoff's voltage law in terms of voltage rise and voltage drop

Voltage rise = voltage drop

n Three cells are connected as shown

on the right

This is an example of what type

connection? (check the correct answer)

series ______

parallel _____ parallel

series-parallel _______

n Resistors are connected to a power supply as

shown on the right.

This is an example of what type

connection? (check the correct answer)

series ____ parallel ___

series-parallel _______ series-parallel

Part 3: Electronics Symbols

Electronic symbols are used extensively in circuits to represent various electrical devices and components. Provide the name of each symbol in the space below each symbol.


Resistor	Inductor	AC Power	Ground	Cell

Capacitor	Variable Capacitor	Potentiometer	Voltmeter	Ammeter

Part 4: Circuit Analysis - AC with RL and RC Circuits

n Assume that you have 4 coils, each with inductance L.

Ø Give an expression below for the total inductance, L_T if they are connected in series

L_T = L + L + L + L = 4L

Ø Give an expression below for the total inductance, L_T if they are connected in parallel.

1/L_T = 1/L + 1/L + 1/L + 1L = 4/L

L_T = L/4

n There is a white canister on the pole shown on the right.

This is a picture of a _________________________________

Transformer

n Assume that you have 4 capacitors, each with capacitance C.

Ø Give an expression below for the total capacitance C_T if they

are connected in series.

1/C_T = 1/C + 1/C + 1/C +1/C = 4/C

C_T = C/4

Ø Give an expression below for the total capacitance C_T if they are connected in parallel.

C_T = C + C + C + C = 4C

n Assume that the voltage on the lines outside a residence is 2400 volts and that it must be reduced

to 120 volts for use in a residence.

To do this a transformer is to be used.

If there are 500 turns on the primary side of the transformer, how many turns should be on the

secondary side?

V_S/V_P = N_S/N_P gives N_S = VsN_P/V_P = (120)(500)/2400 = 25 turns

Part 5: Extra Credit

n A picture of ________________________________________ appears on the first page of this

quiz. Nikola Tesla

n Where was this person born (what country)? __________________________ Serbia