Page 42 - 0419

2019 ‫מועד אביב‬ - 41 - ‫ פרק ראשון‬- ‫אנגלית‬

Text II (Questions 18-22)

(1) Minerals are the substances that rocks are made of. One of the most common
minerals on earth is quartz, which is found in a wide variety of rocks. Quartz may be
colorless but also occurs in virtually every color. It may be transparent – clear enough
to see through; translucent – allowing only some light to pass through; or completely

(5) opaque. Quartz has long been valued for its beauty. Some types of quartz – such as
amethyst, which is purple, and citrine, which is yellow, orange, or brown – are
considered gemstones. These are used to make jewelry, as are stones such as onyx and
agate, in which quartz is layered with other minerals.

Quartz is extremely durable and hence is suitable for a vast array of household
(10) and industrial applications. It is harder than most other natural substances and is

therefore an excellent raw material for manufacturing abrasives: crushed quartz is used
to make sandpaper for smoothing softer materials like wood, and cleaning products that
scrub off dirt. Quartz sand is essential to the production of glass and ceramics. Because
it is also resistant to heat, quartz is used in the manufacture of refractory bricks, which
(15) line fireplaces and furnaces.

Transparent quartz is used for making lenses. The curved surfaces of a lens bend
light, magnifying objects and therefore making them easier to see. Remains of quartz
lenses dating back 4,000 years have been found in Syria and Egypt. In Italy, quartz
lenses were set in frames and worn as eyeglasses by the late 13th century. Today, quartz

(20) lenses are used in many precision optical devices ranging from microscopes to cameras.

One of the most extraordinary characteristics of quartz is its capacity to generate
electricity. In the late 19th century, it was found that when mechanical pressure is
applied to a quartz crystal, electricity is produced. This is known as the piezoelectric
effect, from the Greek word piezo, meaning push. The opposite phenomenon is called

(25) the reverse piezoelectric effect. Passing an electric current – for example, from a
battery – through a quartz crystal results in mechanical pressure that causes the crystal
to expand and contract at regular intervals. These vibrations drive the timekeeping
mechanism of quartz clocks and watches. It is the reverse piezoelectric effect that
makes them so accurate.

Questions

18. Based on the information in the text, which of the following would be least likely to

contain quartz?

(1) a scientific instrument that is heated to very high temperatures
(2) a telescope designed to see faraway planets
(3) a timing device in a computer
(4) a tool to test the level of air pollution

)‫© כל הזכויות שמורות למרכז ארצי לבחינות ולהערכה (ע"ר‬
.‫ בלא אישור בכתב מהמרכז הארצי לבחינות ולהערכה‬- ‫ כולה או חלקים ממנה‬- ‫ או ללמדה‬,‫אין להעתיק או להפיץ בחינה זו או קטעים ממנה בכל צורה ובכל אמצעי‬