Electronics Information 1

A resistor marked 2.5K ohms has the value of

2.5K ohms is 2,500 ohms. K = 1 kilo, or 1,000.

A 5,000 BTU air conditioner can efficiently cool up to 150 square feet, or a 10-foot x 15-foot room. What does BTU stand for?

A British thermal unit is the amount of heat required to raise the temperature of 1 pound of water by 1 degree Fahrenheit. A basic rule of thumb for selecting a room air conditioner is to use a 6,000 BTU unit for 200 square feet, a 7,500 BTU unit for 300 square feet, and a 10,000 BTU unit for 450 square feet.

How wide is the full AT motherboard?

A motherboard is the physical arrangement in a computer that contains the computer's basic circuitry and components. Motherboards come in various sizes and component arrangements, referred to as form factors, to fit standard case sizes, components required, and so on. AT is a standard form factor that has a width of 12 inches and a length of 13.8 inches.

A motor is a type of

A motor is a transducer that converts electrical energy to mechanical energy.

What is used to measure current that is going through a circuit?

A multimeter includes several pieces of test equipment, including an ammeter, which measures inline current.

Made from a variety of materials, such as carbon, this inhibits the flow of current.

A resistor is so named because it resists (or inhibits) the flow of current.

Which one of the following is an active element?

Active elements are electronic devices that can create energy (such as voltage supplies and current supplies). Passive elements are electronic devices that cannot create energy.

A transistor is also called a/an

Amplifier is another name for transistor.

When a circuit breaker trips, in what position will you find the operating handle?

Conventional circuit breaker handles have four positions: on, off, trip, and reset. When tripped, the handle moves to the middle position.

If a 120-volt current is protected by a 25-amp circuit breaker, what's the largest number of watts an appliance can safely use?

Determine the wattage that could cause the circuit breaker to trip with this formula: Watts = Volts × Amps, or 120 × 25 = 3,000 watts.

Which electrical component allows current to flow in only one direction?

Diodes allow electricity to flow in only one direction.

Electricians use the term low potential to refer to

Electric potential is called voltage. Electricians use the term low potential to refer to electrical devices that put out fewer than 600 watts of electrical power.

To measure electrical power, you would use a(n)

Electrical power is measured in watts, so you use a wattmeter. An ammeter measures current (in amps), an ohmmeter measures resistance (in ohms), and a voltmeter measures voltage (in volts).

Power is usually measured in

Electrical power, which is measured in watts, is the rate at which electrical energy is generated or converted to another form.

Electromotive force is another way of saying

Electromotive force is the difference of potential, so the term is another way of saying voltage.

The heat effect of current occurs

Heat effect occurs when electrical current must overcome the resistance of the wire. Heat effect can be quite obvious or very subtle.

In the U.S., all metal equipment, electrical or not, connected to a swimming pool must be

Heaters, pumps, stairs, diving boards, railings and rebar, among other things, must be bonded together by a minimum #8 wire for safety purposes.

"LCD" stands for

LCD stands for liquid crystal display. LCDs use liquid crystals formed into light modulation for electronic visual display. The devices, such as computer monitors, televisions, and signages, are thin and flat and come in a variety of sizes.

This special type of diode lights up when a small voltage is applied. It's usually used as an indicator or in a numerical or alphanumerical display.

LED stands for light-emitting diode. LEDs are usually used as power-on indicators and in billboards and electronic road signs.

A primary advantage of using a Li-Ion battery instead of a NiMH battery in your cell phone is

Li-Ion batteries are lighter.

What special type of diode is commonly used to regulate voltage?

Like other diodes, Zener diodes allow current in only one direction, except if the voltage across it is greater than a threshold voltage (called breakdown voltage), at which point current also flows through the Zener diode in the opposite direction. This action allows the Zener diode to regulate voltage.

How much smaller is an MP3 than a conventional CD file?

MP3 files are just about 10% of the size of regular CD files (WAV files), so the correct answer is that they're 90% smaller

Neutral wire is always

Neutral wire is always whitish or natural colored.

What are common names for some primary discrete components used on circuit boards?

Of course, circuit boards have many more parts, such as transistors, transformers, fuses, inductors, and integrated circuits, but these three components — header, receptacle, and via — are the most frequently used parts. A via is the name for a hole on a circuit board, and headers and receptacles allow engineers to program boards or stack more than one board on top of another.

Electronic circuits that produce high frequencies are called

Oscillators produce high frequencies. An amplifier changes the amplitude of a signal. A regulator is a circuit that maintains a constant voltage. A transformer is a device that changes (transforms) the voltage at its input side to a different voltage on its output side.

A light bulb is 60 watts. Operated at 120 volts, how much current does it draw?

Power = Current × Voltage or, written another way, Current = Power ÷ Voltage. Plug in the numbers and do the math: 60 watts ÷ 120 volts = 0.5 amperes.

"RAM" stands for

Random access memory is a term used to define computer data storage. The information stored can be accessed anytime, regardless of physical location and relevance, using integrated circuits.

The purpose of a rectifier is to

Rectifiers change alternating current (AC) to direct current (DC).

Which of the following is a type of resistor?

Rheostats — Choice (C) — and potentiometers are the two types of resistors. Potentiometers are commonly used to control electrical devices such as volume controls. Rheostats, on the other hand, are designed to handle much higher voltage and current, such as in electric motors.

Which of the following isn't a component of a DC motor?

Rotor bars are only on AC induction motors, not DC motors.

Newer cellphones contain a removable memory card, which is often called a/an

SIM stands for Subscriber Identity Module. The card contains information such as your phone number, your billing information, and your address book. The card makes it easier to switch from one cellphone to another.

What will happen if you operate an incandescent light bulb at less than its rated voltage?

The bulb will burn dimmer because its full potential isn't used; it'll last longer for the same reason.

What is a "cold" solder joint?

The cold solder joint is a long-time enemy of technicians. When solder is "cold", it's dull and bumpy in appearance. The solder's strength is much weaker and is likely to break if the board is put under even minimal stress.

All electrical circuits must have which three components?

The components of a basic circuit are a source of voltage (such as a battery), current (which will flow in a completed circuit), and resistance to current (at least one electrical component, such as a resistor).

A number-12 wire, compared to a number-6 wire

The larger the number, the smaller the diameter of the wire.

Which wire is smallest?

The smaller the wire, the larger the number.

Voltage is sometimes referred to as EMF, or electromotive

The term EMF, or electromotive force, is attributed to Italian physicist Alessandro Volta. Today people generally use the term voltage instead. Can you guess where that name came from?

This is a type of semiconductor in which the flow of current can be controlled through a base or gate terminal. It's usually used for electronic switching or amplifiers.

The transistor is the basic element in most logic circuits and is what makes the microprocessor and modern computers possible.

In the United States, what is the specification for an electrical outlet in a bathroom near a sink?

This is code prescribed by the NEC (National Electric Code). Outlets within 6 feet of a sink need to be GFCI protected for safety reasons.

Electricians refer to bells and buzzers as

Transducers convert one type of energy (electrical, electromechanical, electromagnetic, photonic, photovoltaic) to another. For example, an electric motor is a transducer because it converts electrical energy to mechanical energy. Bells and buzzers are transducers that convert electrical energy to sound energy.

A device that transforms energy from one form to another is called

Transducers, which transform energy, can be switches, strain gauges, temperature sensors, or inductive switches.

A megahertz (MHz) is

Used as a radio-frequency unit and a measure of the clock-speed for a computer microprocessor, a megahertz is a million cycles of electromagnetic currency alternation per second, or 1,000,000 hertz.

"CPU" stands for

Used since the 1960s, the term central processing unit (CPU) refers to the primary element of a computer that carries out the main instructions and functions.

Ohm's law states

Voltage = Current × Resistance

If you plug an appliance designed for AC into a DC power source, the appliance

When DC is applied to an AC appliance, the resistance is lower, so more current flows through the wire and heat builds up.

Transistors contain at least three terminals called the

base, emitter, and collector.

What must exist in order for electricity to flow?

n a closed circuit, current flows from the positive side of the power source to the loads, and then it's wired into the circuit and goes back to the negative side of the power source. When a circuit is open, the charges can't travel from one side to the other.

Most semiconductors are constructed out of

silicon.

A device that transfers electrical energy from one circuit to another through inductively coupled conductors is called a/an

transformer.

To control a light fixture from two different wall switches, you should use

two three-way switches.