Answer to Question #127155 in Electric Circuits for maryem

Question

1. According to Ohm’s law...
(a) ... resistance is ___________ (proportional or inversely proportional?) to current if voltage is held constant.
(b) ... current is ___________ (proportional or inversely proportional?) to voltage if resistance is held constant.
(c) ... voltage is ___________ (proportional or inversely proportional?) to resistance if current is held constant.
2. If you constructed either of the circuits from this lab in real life, and you allowed the current to run for a very long time, the circuit components would heat up. How would this affect the measurement of the current? Assume carbon resistors. (Hint: You will need to look up the temperature coefficient of resistivity for carbon.)

Answer 1

1.

(a) resistance is inversely proportional to current if voltage is held constant.

(b) current is proportional to voltage if resistance is held constant.

(c) voltage is proportional to resistance if current is held constant.

2.

$I=U/R=U/(R _ 0 ( 1 + α Δ T ))$ for carbon $\alpha=-0.0005K^{-1}$.

Therefore, when the temperature is increased, the carbon resistance will decrease, respectively, the current will increase.