Monday, February 22, 2010
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The quiz and answer is: HAM FEST JULY 31
73's
Quiz and testing resource for Ellijay Amateur Radio Society, Ellijay, GA. USA
The answer is c. Two main things to consider with this question: First, how to calculate the total resistance needed and Second the wattage of the resistor. The total resistance is where Question 2 below comes in. As to the wattage, if you need a 1 watt resistor, you wouldn't want to use a ½ watt resistor in this particular case. So you could eliminate the answers with 1/2 watt in them right away. That would make the right answer c.
The answer is a. The general rule for resistances is, resistors in series ADD their resistances and resistors in parallel DIVIDE their resistances. Since a 50 Ohm resistor is needed, the two 100 Ohm resistors in series would add up to 200 Ohms. Not what you want. So, the answer must be (a) Parallel. By the way, the formula for figuring the final value of two resistors in parallel is as follows. First, lets name one resistor R1 and the other R2. The formula is, R1 times R2 divided by R1 plus R2. In this case R1 = 100 Ohms and R2 = 100 Ohms. So R1 times R2 (100 x 100) equals 10,000. Next R1 plus R2 (100 + 100) equals 200. Finally, divide 10,000 by 200 and you get 50 Ohms.
The answer is b.
The answer is a. 468 divided by 14.200 = 32.9 feet or 33 feet rounded.