hvac electrical

8/2/2019 Hvac Electrical

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1.A molecule may contain one or more ____________.: Atoms2.A region of space influenced by an electric force d efines a(an) _____.: Electric field of forces ( Electrostatic and/or dielectric )3.An ampere may be defined as __________.: One coulomb flowing past a fixed point in a conductor in one second. (one coulomb per second) or The flow of one coulomb (or 6.28 x 1018 electrons)past a fixed point in a conductor in one second.4.Artificial magnets include both __________ and __________ .: Permanent and Electromagnets (temporary)5.Can a single magnetic pole (north or south) exist by itself?: No, all magnets have at least two poles6.Describe a magnetic circuit.: A magnetic circuit is a complete path through which magnetic lines of force may be established under the Influence of a magnetic field.7.Describe a magnetic field.: Imaginary lines along which a magnetic force acts. Emanate from the north pole and enter the South pole, returning to the north pole through the magnet.8.Describe an electromagnet: An electromagnet is a coil of insulated wire wound around a soft iron core.9.Describe how a photoelectric voltage is produced.: Photosensitive metal is exposed to light, electrons are dislodged from the metal causing the material to become positively charged and an electricforce is created.

10.Describe how a thermocouple produces an electric current.: When a length of metal, such as copper, is heated at one end, electrons tend to move away from the hot end to ward the cooler end. Thisis true of most metals. However, in some metals, such as iron, the opposite action takes place and electrons tend to move toward the hot end. The negative charges move through the copper away fromthe heat and through the iron toward the heat.11.Electric current is defined as ___________.: The flow of electrons through a conductor.12.Electricity produced by chemical action is provided by cells and Batteries. Explain the difference between cells and batteries.: Cells produce small amount of voltage and are stacked in batteries toprovide for high voltage and current levels. A battery is comprised of a number of cells connected in series.13.Electromotive force (EMF) is also called ________ or ________.: Voltage or difference in potential14.External to the body of the magnet itself, magnetic lines of force are directed from the _______________pole to the ____________pole.: North to South15.How can a sensitive instrument be shielded from magnetic fields?: By placing a soft iron case around the instrument.16.How is a piezoelectric EMF Produced?: It is produced by compressing or decompressing crystals of certain substances.17.How is static electricity commonly produced?: By rubbing two materials together, such as glass and silk.18.If an electric force acts on metallic atoms in a conductor, how do the Outer electrons of these atoms respond?: Electrons in the outer orbits are forced out of orbit, and become free19.In an electric circuit, how is current related to potential difference?: Current is directly proportional to the applied voltage20.In drawings that depict an electric field, arrows represent lines of force. The polarity of the field is indicated by showing the arrow pointing from __________ to ___________.: + to -- ( This isopposite to current flow )21.In what way is a primary cell different from a secondary cell?: Primary cells are dry and are not usually rechargeable. Secondary cells are wet and are rechargeable.22.List five examples of materials that are good electrical conductors.: Silver, copper, Gold, aluminum, platinum, and iron23.List five examples of materials that are good electrical insulators.: Rubber, glass, air, wood, paper, plastic24.List the six commonly used methods of producing voltage.: Friction. Produces static electricity.Pressure. Piezoelectricity Heat. Thermoelectricity Light. Photoelectricity Chemical action. Battery

Magnetism. Induction25.Lodestones, containing the mineral magnetite, are __________magnets: Natural26.Name 4 scientists that established laws that describe the characteristics of electricity: Coulomb, Faraday, Kirchhoff, Lenz, and Ohm27.Pieces of magnetic material that retain their magnetism are called: Permanent magnet28.State Coulomb's Law.: Charged bodies attract or repel each other with a force that is directly proportional to the product of their charges, and is inversely proportional to the square of the distance.29.State Lenz's Law.: The induce EMF in any circuit is always in a direction opposite the effect that produced it.30.The central core of an atom contains ________ and __________.: Protons and neutrons31.The central core of an atom is called the ________________.: nucleus32.The direction of a current induced by an expanding magnetic field is Opposite of the current which produced the magnetic field. This reversal in polarity is referred to as.: Counter electromotiveforce (CEMF) or Back EMF33.The earth's magnetism produces a(n) ____________surrounding the earth.: Magnetic field34.The entire quantity of magnetic lines of force surrounding a magnet is called ________________: Magnetic flux.35.The entire quantity of magnetic lines of force surrounding a magnet is called .: Flux Density 36.The law that describes the direction of electric force acting on charged Bodies is called the law of electrical attraction and repulsion. State the Law.: Like charges repel each other and unlike chargesattract each other.37.The laws that describe the direction of magnetic force acting on Magnetic poles are called the laws of magnetic attraction and repulsion. State the laws.: 1. Like poles repel2. Unlike poles attract3. Forces between two poles decrease rapidly as the poles are separated from each other.38.The magnetic flux produced by a current in a coil is proportional to the square of the number of turns of wire in the coil. This phenomenon is called .: Self inductance39.The unit of measurement for electric charge is the ____________.: Coulomb40.Using the equation in the previous question, calculate the quantity of Electric charge that flows through a circuit in 60 seconds if the current in the circuit is 5 amperes.: Q = It Q = 5 x 60 Q = 30041.What are the three fundamental requirements for producing a voltage by Means of magnetism?: 1. There must be a conductor in which the voltage will be produced.2. There must be a magnetic field in the conductor's vicinity.3. There must be relative motion between the field and the conductor.42.What is the charge (positive, negative, or neutral) of an insulated body Of matter if it contains more electrons than protons? If it contains more Protons than electrons? If it contains an equalnumber of protons and Electrons?: Negative, Positive, Neutral43.What is the equation for calculating electric charge?: Q = It (Q = Electrical charge in coulombs, I = current in amperes, t = time is seconds)44.What is the smallest particle of a compound?: The Molecule45.What is the smallest particle of an element?: The Atom46.What property of conductors distinguishes them from insulators?: Conductors permit the free motion of electrons, and insulators restrict the free motion of electrons.47.When a current is initiated in a coil of wire, a magnetic field expands around it. When the current is terminated, the magnetic field collapses. In a second coil adjacent to the energized coil, a currentis induced in both cases. This phenomenon is called ______________ .: Mutual Induction48.Which magnetic theory contains the idea that magnetic materials are composed of large groups of atoms with their magnetic poles oriented in the same direction?: The domain theory 49.Which of the three subatomic particles has a negative charge: Electrons50.Who were the first people to record observations of electric forces?: The ancient Greeks1.A Current of 2 A flows through a lamp that has a resistance of 25 ohms. Determine the power consumption: 100 watts ( P = I2 x R )2.A parallel circuit has three branches, all connected to a 20 V source. Branch A includes a lamp with a resistance of 5 ohms. Branch B includes A lamp with a resistance of 10 ohms. Branch C includesa lamp with a Resistance of 20 ohms. Determine the voltage and current in each branch and the total current.: A = 20v/4amps B = 20v/2amps C = 20v/1amp Total current = 7amps3.Amperage is the measurement of ___________.: Electron flow through a conductor4.Determine the power used by a lamp that has a resistance of 20 ohms and a 12 V source.: 7.2 watts ( P = E2 / R )5.How is a parallel circuit identified?: It has more then one path for current.6.Resistance is defined as the ____________.: Opposition to the flow of electrons in a conductor.7.State Kirchhoff's Law of voltages that pertains to a series circuit.: The sum of the voltages in a series circuit is equal to the source voltage.8.The current in a simple circuit is 2 A, with a 24-V potential. What is the Resistance?: 12 Ohms ( R = E/I )9.There are two light bulbs in a series circuit. Bulb A has a resistance of 10 ohms and bulb B has a resistance of 20ohms. If the current in bulb A is 1.5A, what is the current in bulb B?: 1.5Amps,

Components that are connected in series with each other will always have the same current flow.10.Use Ohm's Law to calculate the voltage across a lamp with a resistance Of 20 ohms and a current of 2 A.: 40 volts ( E = I x R )11.Voltage is the measurement of ____________.: Electrical pressure12.Wattage is the measurement of ____________.: Power ( the rate of doing work) in a electrical circuit.13.What is direct current?: Current that flows in one direction, from negative to positive.14.What is the most apparent characteristic of a series circuit?: There is a single path for the current.15.Write the equation used to determine power in a simple resistive circuit when only current and voltage are known.: P = I x E16.Write the equation used to determine power in a simple resistive circuit When only resistance and current are known.: P = I2 x R 17.Write the equation used to determine power in a simple resistive circuit when only resistance and voltage are known.: P = E2 / R 18.Write the Ohm's Law equation used to solve for: a) voltage, B) current, And c) resistance.: a) E = I x R b) I = E/R c) R = E/I1.Calculate the capacitive reactance of a 500 mf capacitor to a 120 Hz current.: XC = 1/2pfc = 1 / 23.1416 120 .0005 = 1 / 6.2832 .06 = 1 / .376992

= 2.6525761 ohms2.Calculate the impedance of a coil that has a dc resistance of 40 ohms a capacitive reactance of 400 ohms, and an inductive reactance of 200 ohms.: Z = R2 + (XC - XL)2 = 402 + (400 - 200)2 =1600 + 40,000 = 41,600= 203.963.Calculate the inductive reactance of a 500 millinery coil to a 120 Hz current.: XL = 2pfL = 23.1416 120 .5 = 6.2832 60 = 376.992 Ohms


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4.Calculate the power factor of a load from these instrument readings: Voltage = 240 V, current = 20 A, actual power = 4,000 W: 83.33 %5.Counter electromotive force is also known as?: Back EMF6.Define impedance.: The total opposition to the current flow in an ac circuit.7.Define inductance.: Opposition to any change in existing current flow.8.Define power factor: The ratio of actual power being used, to the power which is apparently being used9.Define reactance.: Resistance introduced into an ac circuit by a specific component.10.Describe the phase relationship of current and voltage in a purely Capacitive circuit.: Current leads voltage by 90 degs.11.Describe the phase relationship of current and voltage in a purely inductive circuit.: The voltage waveform is leading the current by 90 degs. (ELI the ICE man)12.Electric utility companies in the U.S and Canada supply alternating current with a standard frequency of _______________.: 60 Hertz13.How does inductance vary with the number of turns in a coil?: The inductance varies as the square of the number to turns.14.If the inductance of a coil is increased, the inductive reactance ____________.: Increases

15.In calculating the total inductance of a circuit, you need to remember that inductors follow the same rules as _________ .: Resistors16.Inductive reactance is measured in?: Ohms17.Iron-core inductors are sometimes called _______________: Choke coils18.List five factors that affect the inductance of a coil.: The number of turns in the coilThe diameter of the coilThe length of the coilThe type of material used in the coreThe number of layers of windings in the coils.19.List two reasons why three phase power is preferred for high demand Loads.: Easier to transmit and compensates for higher voltage and current requirements.20.Most ac voltmeters and ammeters read values that are equivalent to dc. These are also known as ____________ values.: RMS (Root Mean Square) or Effective. It is 70.7% of the peak-to-peak value of the sine wave.21.Name and write the symbol for the two kinds of reactance other than Resistance.: XC = Capacitive reactance XL = Inductive reactance22.Reactance is measured in _____________: Ohms23.State Lenz's Law: The induced EMF in any circuit is always in a direction opposite the effect that produced it.24.The basic unit of measurement for inductance is the ______________: Henry 25.The induction of an EMF in one coil or conductor by the flux field from another coil or conductor is called?: Mutual Induction26.The units of measurement for frequency are _______________.: Hertz27.What happens to inductance if you double the length of a coil while keeping the same number of turns?: It decreases.28.What happens to inductive reactance when frequency is increased?: It increases in proportion to the increase of frequency 29.What is it that alternates in alternating current?: Voltage30.What is the difference between apparent power and actual power?: Apparent power is the product of applied voltage and current. It does not take into account the phase angle between voltage andcurrent that exists. Actual or useful power is measured with a wattmeter.31.What is the equation for calculating inductive reactance?: XL = 2pifL

32.When a voltage is induced in the conductor carrying the current, the phenomenon is called?: Self - inductance1.According to Ohm's Law, one volt equals one ampere times one _____.: Ohm2.An electric circuit has two 25 Ohm resistors and one 50 ohm resistorConnected in series. What is the total resistance of the circuit?: 100 ohms RT = R1 + R2 + R3 .........3.Convert 2,850 watts to kilowatts.: 2.85 Kilowatts4.Define power: It is the rate of doing work, and work is usually expressed as the means of overcoming mechanical resistance.5.If 5,000 watts of power are used for 48 hours, solve for kilowatt hours.: 240 kWh6.If the diameter of a wire is increased, does its resistance increase or decrease?: Decrease7.If the length of a wire is increased, does its resistance increase or decrease?: Increase8.If the total voltage in a simple circuit is 120V and the total resistance is 40 ohms, solve for power.: 360 watts P = E2 / R 9.Is the total voltage drop in a simple parallel circuit greater than, less Than, or the same as the voltage drop across any single resistance: The same as.10.One horsepower in mechanical energy is equal to _____________ watts in Electrical energy.: 746 Watts11.Overcoming resistance requires _______________.: Work (Measured in Watts)12.State the three equations derived from Ohm's Law for calculating power.: P = Esq / R; P = IE; P = Isq R 13.The resistance of a conductor depends on at least four factors. Name them.: * The length of the wire.* The diameter of the wire.* The material the wire is made of.* The temperature of the wire.14.Using E for voltage, I for current, and R for resistance, complete the Following three equations derived from Ohm's Law:: E = I * R I = E / R R = E / I15.What is the total resistance of the circuit if the same three resistors are Connected in parallel?: 10 ohms1."L1" and "L2" in a ladder diagram indicate the ____________ and

____________, respectively.:Line and the Load2.An electric circuit must have a source of electrons, a device in which theElectrons do work, and a path for the electrons to follow. A practicalCircuit also requires ______________.: A device that controls the load in the circuit3.An electrical connection at an intersection of lines (conductors) in a Schematic is indicated by a(n) ________________.: A Dot

4.Diode:


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5.DPDT switch:

6.Fusable link:7.In a schematic, the designation "SPST" indicates a _____________.: Single Pole Single Throw Switch8.In any electric circuit, it is important for safety purposes that the switch Be placed in the ____________ side of the electrical load.: Line side9.Name three types of wiring diagrams.: 1. Ladder2. Line diagram3. Installation diagram

10.Normally closed set of points:

11.Pressure switch that opens on increase in pressure.:

12.SPDT switch:13.The letters "NC" placed next to a switch or relay symbol in a schematic Indicates a _____________ device.: Normally Closed14.The list of letters that identifies the components represented in aSchematic is called the ____________.: Legend


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15.Thermostat that opens on a drop in temperature.:

16.Thermostat that opens on an increase in temperature.:17.What are the five basic components to any schematic?: 1. A power supply 2. A path for the power3. A load or component that operates from the power.4. A switch or component that interrupts the power to the load.5. A legend or key that explains what the various symbols and abbreviations used in the schematic mean.

18.What is the symbol that represents a "DPST" switch.:

19.What is the symbol that represents a fuse.:

20.What is the symbol that represents a ground.:

21.What is the symbol that represents a transformer.:22.Which one of the four basic types of wiring diagrams is of primary Interest to the service technician?: Schematic or Ladder diagram1.After you have notified the appropriate personnel that you will be Working on a piece of equipment, what are the steps that you should follow to complete the lockout/tagout procedure correctly?:Turn off the power, and attach the lock out device to the circuit breaker or disconnect switch.

Put your own padlock on the lock out device and lock it with your own key.

Tag the equipment with appropriate warning signs, stating that the equipment is not to be energized or operated and that locks, tags, and other safeguards are not to be tampered with or removed.2.An electric shock of as little as _______ mA can cause the inability Of the victim to "let go" of the circuit.: 5mA 3.Electrical fires are classified as _____________ fires.: Class C fires4.How does a ground fault circuit interrupter work?: It senses a imbalance of current flow between the hot and neutral wires, which indicates current flow from hot to ground. This imbalance opensthe circuit breaker before current reaches dangerous levels.5.List the three general types of hazards associated with electricity.: Electric shock, Burns, and related accidents caused by a shock.6.The condition marked by the rapid, uncoordinated twitching of the heart muscle, resulting in a lack of circulation and pulse, is known as _____________.: Ventricular fibrillation


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7.The severity of an electric shock depends not just on the amount of Current that passes through the body, but also on the __________ andthe ___________.: Path the current takes and the duration of the current flow.8.What color is the hot wire in an electric circuit? What color is the neutral Wire? What color is the grounding wire?: Black or Red, white, green9.What should you do if the victim of an electric shock is still in contact With the electrical source?: Turn off the power first, if possible, or move the victim away with a piece of some dry, nonconductive material.10.What type of extinguishing agent is normally used to fight electrical fires?: Carbon Dioxide ( CO2 )11.When is it permissible to use improperly sized fuses?: Never12.When you use electric power tools, you must be sure that they are ____________ or __________ tools.: Grounded or double-insulated.1.A material's resistance is based on its __________ and ________________ .: Shape (length and cross-sectional area) and composition

2.A resistor's color bands are (left to right) brown, red, orange, and silver. What is its resistance?: 12,000 ohms 10%3.Be able to solve for total resistance in a complex parallel/series circuit.: Practice makes perfect4.Name two types of fixed resistors.: Composition or carbon resistors and wire-wound.5.The total resistance of a parallel circuit is always __________than the ________ resistance in any of the branches.: Less than the smallest6.To find the current in any single-phase circuit, you must divide the ________by the ________________ .: Voltage by the Current7.To find the power in any single-phase circuit, you must multiply the ____ by the _______ .: Voltage by the Current8.What are the most common colors for a resistor's third band?: Red, orange and yellow 9.What are the two basic types of variable resistors, and what is the main difference between them?: Potentiometer and rheostat, The potentiometer has 3 terminals, the rheostat only 210.What is the total resistance of a circuit in which a 5-Ohm resistor, a 32-Ohm resistor, and an 8 0hm resistor are connected in series?: 45 Ohms11.What is the total resistance of a circuit in which a 20-Ohm resistor, a 40-Ohm resistor, and an 80-Ohm resistor are connected in parallel?: 11.43 ohms12.What is the total resistance of a circuit in which one 40-Ohm resistor and one 20-Ohm resistor are connected in parallel?: 13.33 Ohms ( 40 x 20 40 + 20 )13.What is the total resistance of a circuit in which two 25-Ohm resistors are connected in parallel?: 12.5 Ohms (Two resistors of equal value connected in parallel always equals the value of one of the resistors.14.What type of resistor has several different fixed resistances in one package?: Tapped fix resistor15.When calculating the total current in a balanced three-phase circuit, you must use a constant factor of: 1.7316.Write the equation for calculating power in a dc circuit if current and voltage are known.: P=I x E17.Write the equation for calculating the total resistance of a series circuit.: RT = R1 + R2 + R3 + ETC.....1.. If two 400-tlF capacitors are connected in series, what is their total capacitance?: 200 uF2.. If two capacitors rated at 125 V are connected in series, what is their total voltage?: 250V 3.. If two capacitors with the same voltage rating are connected in parallel, what happens to the total voltage rating of the two?: It remains the same.4.. In a capacitor-start, capacitor-run motor, are the capacitors connected in series or in parallel during start-up?: In parallel.5.A capacitor increases the starting torque of a motor to % of its full-load power: 300 to 500%6.A capacitor is a device that stores a quantity of _______________ .: Electrons.

7.A capacitor is made up of two metal plates separated by a(n) ____________ .: Insulator8.A motor start capacitor is a(n) _____________________ capacitor.: Electrolytic.9.A permanent split-capacitor motor operates as a(n) -phase motor.: Two10.A start capacitor usually has a(n) __________ value of capacitance and a(n) ___________voltage rating than a run capacitor.: High ...lower11.A typical start capacitor is designed for a maximum of starts per hour.: 2012.Capacitance is usually measured in __________: Microfarads13.Capacitors connected in parallel result in a higher capacitance because the _______________has been increased.: Overall plate area14.Define capacitance.: The ability to store electrical energy in an electrostatic field15.Do electrons flow through a capacitor?: No16.Does a run capacitor increase or decrease current draw?: Decrease17.Does a run capacitor reduce power consumption?: No18.Does a split-phase motor have a high starting torque or a low starting torque?: Low 19.Does a start capacitor increase or decrease starting current?: It decreases starting current20.How can a capacitor's value be increased?: By increasing the size of the plates and decreasing the distance between them.21.How long can a capacitor remain charged?: Indefinitely 22.If two capacitors are connected in series and one fails due to a short, what may happen to the other one?: It generally will short out also.23.On a motor equipped with both a start capacitor and a run capacitor, which capacitor will have the higher capacitance rating?: The start capacitor.24.Start capacitors have typical tolerance ratings of _______________ %: 20 to 25%25.The capacitor with the _________voltage rating determines the maximum safe operating voltage that can be applied to a parallel circuit: Highest26.The life of a motor start capacitor will be shortened if the voltaqe across the capacitor exceeds % of the rated voltage: 15%27.The terminal of a capacitor marked with a dot should always be connected to the _____ side of a circuit.: Line28.The unit of measurement normally used in rating the capacitance of a capacitor is the ____________ .: Microfarad (uF)29.The working voltage of a series circuit is the ____________ of the working voltages of the individual capacitors.: Sum of the working voltages of the individual capacitors.30.What are the four main problems associated with capacitors?: They may be open, shorted, leaking, or undergo a change in value.31.What are the typical ranges of capacitance and voltage for a run capacitor?: 5 to 50 uF and 370 to 440 V 32.What are the typical ranges of capacitance and voltage for a start capacitor?: 50 to 380 uf and 110 to 330 V 33.What determines the safe working voltage of a capacitor?: The strength of the dielectric material.34.What happens if the potential difference across the plates is greater than the dielectric can withstand?: The dielectric will break down and a short circuit will occur.35.What happens to the capacitance of a capacitor if the plate area is doubled, all other factors being equal?: The capacitance doubles.36.What happens when a capacitor becomes shorted?: The dielectric breaks down and the plates short to each other37.What is a picofarad?: A measure of capacitance equel to a millionth of a millionth of a farad (or one one-millionth of a microfarad).38.What is the dielectric constant of air?: One, ( it is the standard )39.What is the purpose of a run capacitor?: It improves the power factor of a motor.40.What is the recommended value (in ohms) of a resistor used to discharge a capacitor?: 15,000 ohm41.What is the total capacitance of a circuit in which a 5 uf capacitor, a 13 uf capacitor, and a 12 uf capacitor are connected in parallel?: 30 uF42.What is the total capacitance of a circuit in which a 15-pF capacitor and a 10-pF capacitor are connected in series?: 6 pF43.What is the total capacitance of a circuit in which a 30 uF capacitor, a 20 uF capacitor, and a 10 uf capacitor are connected in series?: 5.46 uF44.What is the working voltage of a capacitor?: The maximum voltage that may be safely applied across the capacitor without breakingdown the dielectric between the plates.45.What should you do before performing the ammeter/voltmeter test?: Use an ohmmeter to make sure that the capacitor is not shorted.46.What three factors determine the capacitance of a capacitor?: The area of the plates,The distance between the plates,The dielectric constant of the material between the plates.47.What two factors determine the size of a run capacitor?: Motor horsepower and applied voltage.48.What will happen when you use an analog ohmmeter to test a good capacitor?: The meter's needle will deflect first toward zero, then slowly back toward infinity

49.What will happen when you use an analog ohmmeter to test an open capacitor?: The meter's needle will not move. (It will stay on infinity)50.When capacitors are connected in parallel, the total capacitance of the circuit is the __________of all the individual capacitances.: Sum51.When capacitors are connected in series, the total capacitance of the circuit is always ________ than the ________ capacitance of any of the individual capacitors.: Less than the smallest52.When replacing a start capacitor, a variance in capacitance of can usually be tolerated.: 10%53.When two capacitors are connected in parallel, what happens to the total capacitance?: It increases54.When you use a digital capacitance meter, a reading of "00.0" indicates a(n) ______________ capacitor.: Open55.When you use a digital capacitance meter, what reading is displayed if the capacitor being tested is shorted?: The digital readout will display a "1" or "1x."56.When you use a neon light tester to test a capacitor, what is the significance of a continuously glowing light?: The capacitor is shorted.57.When you use the ammeter/voltmeter method to determine capacitance, what is the approximate value of the capacitor if the ammeter mads 2.5 A and the voltmeter reads 245 V?: Approximately 27 uF58.Which is the better insulator, a material with a high dielectric constant or a material with a low dielectric constant?: Material with a high dielectric constant59.Why are split-phase motor compressors usually used on domestic refrigerators and freezers?: These applications use capillary tubes and therefore require a lower starting torque.60.Why do start capacitors have a fuse hole?: To allow gases to escape when the capacitor becomes overheated.61.Why should you use a resistor instead of a screwdriver to discharge a capacitor?: There is an internal fusing device inside some capacitors that may blow if thecapacitor is discharged with a screwdriver or jumper wire.


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