1. Put the sentences in right order to make a text.

1. ____ 2) ____ 3) ____ 4) ____ 5) ____ 6) _____

a) Without circuit breakers (or the alternative, fuses), household electricity would be impractical because of the potential for fires and other mayhem resulting from simple wiring problems and equipment failures.

b) As we'll see, the circuit breaker is an incredibly simple solution to a potentially deadly problem.

c) In this article, we'll find out how circuit breakers and fuses monitor electrical current and how they cut off the power when current levels get too high.

d) The circuit breaker is an absolutely essential device in the modern world, and one of the most important safety mechanisms in your home.

e) To understand circuit breakers, it helps to know how household electricity works.

f) Whenever electrical wiring in a building has too much current flowing through it, these simple machines cut the power until somebody can fix the problem.

Unit 8. Instrument panel of a car Text a characteristics of displays

Anything that conveys information can be categorized as a display. However, in a car’s electrical system, the three types most often used are warning and indicator lamps, gauges and buzzers. Displays depend on causing a stimulus, either to the driver's sense of sight (lamps and gauges) or sense of hearing (buzzers). The effectiveness of the device depends on its ability to intrude into the driver’s consciousness and make an impression. Then, if he understands the meaning of the impression, the driver can take the necessary action.

Regardless of the nature of the display device, you must consider several physical characteristics of the display when selecting one. As used in the following text, the term discrimination simply means noticing something and deciding how important it is. In the case of displays, there are several kinds of discrimination you need to consider when designing the instrument panel of your project car.

Visual discrimination of a display depends on its shape, size, colour or indicator-needle position.

A good example of indicator position is the hands on a clock. You soon learn to tell time by the position of the hands, even if there are no numbers on the clock face. The same is true in a car’s instrumentation. For instance, on an oil-pressure gauge you associate needle position with the pan of the dial that’s regarded as safe.

Colour discrimination is often associated with warning and indicator lamps. It is also associated with the needle position on some gauges. That is, some gauges have colour bands printed on the scale, so a quick glance shows you if the needle is in the red, green, or whatever. This way, you can tell status without looking at the numbers on the scale.

Red traditionally represents danger, so warning lamps, such as those used to indicate high temperature or low oil pressure, are often red. Conversely, indicator lamps that merely convey information are usually some colour other than red. For instance, blue is frequently used for headlamp high beams, green for turn signals.

Auditory discrimination, of course, relates to hearing. In a car, a buzzer is either buzzing or it isn‘t. But you can discriminate between differences in the buzzer's frequency (high or low pitch) and its intensity (loud or soft), although these sound qualities aren't often important in a car's information systems.

Relative discrimination means comparing two or more stimuli to each other.

In a car, there's not much need for this, unless you happen to have temperature gauges for both engine coolant and engine oil. Here, a wise driver will make frequent comparisons, because a sudden rise in coolant temperature with little or no immediate change in oil temperature is a good early warning of coolant lots.

Absolute discrimination means taking a reading without comparing it to another reading. This kind of discrimination stands on its own merits. A simplified example is the GEN light used to indicate generator output on a car without a voltmeter or ammeter. If the light is off, you can presume everything is right, if it’s on, something is wrong. It’s either one or the other, so there’s no comparison needed.