NJSLA Practice Test 6
10 free NJSLA practice questions in the real exam format, covering the official content areas, with an explanation for every answer.
Question 1 of 10
Reading Informational TextsPassage 1: Brighter Beams
1For centuries, lighthouses had a serious problem: most of their light was wasted. A keeper could burn the brightest lamp available, but its light spread out in every direction—up into the sky, down onto the rocks, and back toward land. Only a small part of it traveled out across the water, where sailors needed it.
2Early builders tried to fix this with mirrors. A curved metal mirror placed behind a lamp could gather some of the light and push it forward. Mirrors helped, but they had drawbacks. The metal soaked up part of the light instead of reflecting it, and smoke from the lamps darkened the mirrors, so keepers had to polish them constantly.
3A glass lens seemed like a better tool. A lens can bend light and gather it into a strong, narrow beam. But a lens big enough for a lighthouse would have to be enormously thick in the middle. It would be extremely heavy, costly to make, and likely to crack as the lamp heated it.
4In the 1820s, a new design solved the problem. Instead of one thick lens, it used rings of glass prisms arranged around a small central lens, like the rings of a target. Each ring was cut at a slightly different angle so that it bent the light by just the right amount. Together, the rings did the work of a single thick lens while using far less glass. The design became known as the Fresnel lens, after the French engineer who invented it.
5The results were dramatic: because so little light was wasted, ships could spot the beam from much farther away, giving sailors more time to steer clear of danger.
6The new lenses spread around the world. In 1841, the Twin Lights of Navesink, on a high bluff in Highlands, New Jersey, became the first lighthouse in the United States to use a Fresnel lens. After the United States Lighthouse Board was formed in 1852, the lenses were installed in lighthouses across the country.
7Today, many lighthouses use modern electric lights. But in museums and in some working towers, visitors can still see the glittering rings of glass that made the night sea safer.
Passage 2: Augustin Fresnel, the Engineer Who Studied Light
1As a young man, Augustin Fresnel worked as a government engineer, building roads in the French countryside. The work was steady, but it did not hold his interest. In his spare time, he thought about a question that had puzzled scientists for more than a century: what is light?
2At the time, many scientists believed that light was made of tiny particles shooting out from a source, like grains of sand thrown from a hand. Fresnel suspected instead that light traveled in waves, the way ripples spread across a pond. He had no laboratory and little equipment, so he built his own instruments. For one experiment, he used a drop of honey as a lens to focus sunlight into a narrow beam.
3In 1817, the French Academy of Sciences announced a prize for the best explanation of how light bends around the edges of objects. Fresnel entered with a paper based on his wave idea. One of the judges, who believed light was made of particles, used Fresnel’s own math to make a prediction that seemed silly: if Fresnel were right, a bright spot should appear in the very center of the shadow of a small round disk. Surely, the judge thought, that was impossible.
4Another judge, François Arago, decided to test the prediction. He set up the experiment—and found the bright spot exactly where Fresnel’s math said it would be. Fresnel won the prize in 1819.
5That same year, Fresnel was asked to join a group studying how to improve France’s lighthouses. His knowledge of how light bends made him the right person for the job. He realized that a lens did not need to be solid all the way through, because only its curved surfaces bent the light. By cutting the lens into rings of prisms, he could keep the curves and leave out most of the glass.
6In 1823, his first lighthouse lens was installed at Cordouan, a lighthouse on a rocky shoal at the mouth of the Gironde River in France. Its beam was far brighter than that of the mirror system it replaced.
7Fresnel spent the rest of his short career improving his designs. Within a few decades, his lenses were shining from coastlines around the world. An engineer who once studied light in his spare time had changed the way ships found their way home.
Read Passage 1, “Brighter Beams,” and Passage 2, “Augustin Fresnel, the Engineer Who Studied Light.” Then answer the questions.
What is the central idea of Passage 1?