AN ELECTRICAL QUESTION BOARD PHILIP L. BRUCE Long Beach City College, Long Beach, California
T o amp arouse the interest of general chemistry students I have constructed an electrical question board shown in Figure 1. The apparatus consists of a thin wooden panel mounted on a support. The left side of the panel is so arranged that a sheet of standard size typewriter paper containing ten multiple choice questions may be inserted into a frame and covered with a glass. On the right side of the panel are 50 small bolts so mounted that the bolt heads are on the front of the panel. These bolts are arranged in ten horizontal rows with five bolts in each row. The rows, which are numbered from one to ten, correspond to the 10 multiple choice questions. The five bolts in any one row correspond to the five choices given for any one question. Near the top of the panel is a 110-volt, 2-watt neon bulb. On the back of the panel are mounted a 110-volt bellringing transformer and a standard door bell. A flexible insulated wire about 18 inches long immerges from the front of the panel through a hole near the bottom. This wire is terminated by an insulated probe similar to that used on voltmeters. If the electrical conductor on the end of this probe is placed in contact with one of the bolt heads, either the neon light will glow or the bell
NEON BULB 4
110 VOLTS A C
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Wiring Diagram
will ring. Which effect occurs depends on how the bolts have been connected into the electrical circuit. A portion of the wiring diagram which includes only three out of the ten rows of bolts is shown in Figure 2. The electrical connections t o t h e bolts are made with uninsulated #24 copper wire on the back of the panel and arranged in such a manner that one bolt in every row is connected to the neon bulb. The other four bolts in each row are connected to the transformer. The connection to any bolt is made by a single turn of wire around the bolt. By using this admittedly crude wiring system, the board can be rewired for a different set of ;uestiom within five minutes. I n order to reduce the poi:iil,ility oi t.lt.vtriv:~lihovk i t is pl-t+xill,le to connect rhc ~wohr.to t h arwndnl ~ ui(l(. of rhv IlO-volt line. When in use, the question board is placed in the laboratory with a set of questions relating to that part of the course on which the student is to be tested within a few days. The student selects what appears to be the best choice and connects the probe with the corresponding bolt. If his choice is correct, the neon light will glow. If his choice is wrong t-he bell will make an unpleasant noise due to friction tape around the bell. The use of this apparatus is entirely voluntary. However, the fact that it has been used by a majority of the students gives some of its value. ~ ~ ~ indication i
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