Need help with these college Algebra questions.?

Posted on 2016-02-29 19:07:00 in Engineering by KARLI

1. If the resistance in an electrical circuit is held constant, the amount of current flowing through the circuit is directly proportional to the amount of voltage applied to the circuit. When 7 volts are applied to a circuit, 140 milliamperes of current flow through the circuit. Find the new current if the voltage is increased to 9 volts. 
a.63 milliamperes 
b.200 milliamperes 
c.171 milliamperes 
d.180 milliamperes 

2. If the voltage, V, in an electric circuit is held constant, the current, I, is inversely proportional to the resistance, R. If the current is 140 milliamperes when the resistance is 4 ohms, find the current when the resistance is 28 ohms. 
a.80 milliamperes 
b.973 milliamperes 
c.980 milliamperes 
d.20 milliamperes 

3. The intensity I of light varies inversely as the square of the distance D from the source. If the intensity of illumination on a screen 20 ft from a light is 2.8 foot-candles, find the intensity on a screen 50 ft from the light. 

a.7 foot candles 
b.1.12 foot candles 
c. 17.5 foot candles 
d. 0.448 foot candles 

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