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Resistors and Ohm’s Law
Experiment No. 3 Quiz
Student Name _________________________
(1) What parameters does Ohm’s Law relate? (What is Ohm’s Law used for?)
(2) What do you do to test a material to see if it is ohmic? (i.e., Does it follow Ohm’s Law?)
(3) How do you determine the power dissipated by a resistor?
(4) Name an application that requires (a) high resistance, (b) low resistance.
Resistors and Ohm’s Law
Experiment No. 3 Quiz --- ANSWERS
(1)
What parameters does Ohm’s Law relate? (What is Ohm’s Law used for?)
Ohm’s Law describes the relationship between the current (I) flowing through a resistance (R) in response to an applied
voltage (V). If the relationship is linear (i.e., I=V/R), then the resistance is said to be ohmic. Ohm’s Law allows calculation
of any one of the three variables (I, R, and V) given the values of the other two.
(2)
What do you do to test a material to see if it is ohmic? (i.e., Does it follow Ohm’s Law?)
To test a material to see if it is ohmic, you must subject it to two or more tests that measure the current resulting
from different applied voltages. If the calculated resistances, using Ohm’s Law with the measured voltages and currents
are the same, the material is ohmic. Another way is to plot current as a function of applied voltage for three or more
points. If this results in a straight line, then the material is ohmic.
(3)
How do you determine the power dissipated by a resistor?
Multiply the current (I, amperes) flowing through the resistor by the voltage drop (V, volts) across the resistor.
This product is the power (P, watts).
(4)
Name an application that requires (a) high resistance, (b) low resistance.
(a) incandescent light bulbs, electric stove elements, toaster ovens, hair driers, curling irons, steam irons , etc.
(b) electric transmission lines, electrical circuit wiring, measuring devices such as multi-meters, etc.