Applying the science practices: examining resistance
Using the PhET Simulation “Resistance in a Wire”, design an experiment to determine how different variables – resistivity, length, and area – affect the resistance of a resistor. For each variable, you should record your results in a table and then create a graph to determine the relationship.
Test prep for ap courses
Which of the following affect the resistivity of a wire?
Suppose the resistance of a wire is
R Ω. What will be the resistance of another wire of the same material having the same length but double the diameter?
The resistances of two wires having the same lengths and cross section areas are 3 Ω and 11 Ω. If the resistivity of the 3 Ω wire is 2.65 × 10
−8 Ω∙m, find the resistivity of the 1 Ω wire.
Suppose the resistance of a wire is 2 Ω. If the wire is stretched to three times its length, what will be its resistance? Assume that the volume does not change.
The resistance
of a cylinder of length
and cross-sectional area
is
, where
is the resistivity of the material.
Values of
in
[link] show that materials fall into three groups—
conductors, semiconductors, and insulators .
Temperature affects resistivity; for relatively small temperature changes
, resistivity is
, where
is the original resistivity and
is the temperature coefficient of resistivity.
[link] gives values for
, the temperature coefficient of resistivity.
The resistance
of an object also varies with temperature:
, where
is the original resistance, and
is the resistance after the temperature change.
Conceptual questions
In which of the three semiconducting materials listed in
[link] do impurities supply free charges? (Hint: Examine the range of resistivity for each and determine whether the pure semiconductor has the higher or lower conductivity.)
Does the resistance of an object depend on the path current takes through it? Consider, for example, a rectangular bar—is its resistance the same along its length as across its width? (See
[link] .)
Explain why
for the temperature variation of the resistance
of an object is not as accurate as
, which gives the temperature variation of resistivity
.
What current flows through a 2.54-cm-diameter rod of pure silicon that is 20.0 cm long, when
is applied to it? (Such a rod may be used to make nuclear-particle detectors, for example.)
(a) To what temperature must you raise a copper wire, originally at
,
to double its resistance, neglecting any changes in dimensions? (b) Does this happen in household wiring under ordinary circumstances?
A resistor made of Nichrome wire is used in an application where its resistance cannot change more than 1.00% from its value at
. Over what temperature range can it be used?
An electronic device designed to operate at any temperature in the range from
contains pure carbon resistors. By what factor does their resistance increase over this range?
(a) Digital medical thermometers determine temperature by measuring the resistance of a semiconductor device called a thermistor (which has
) when it is at the same temperature as the patient. What is a patient's temperature if the thermistor's resistance at that temperature is 82.0% of its value at
(normal body temperature)? (b) The negative value
for
may not be maintained for very low temperatures. Discuss why and whether this is the case here. (Hint: Resistance can't become negative.)
(a) Redo
[link] taking into account the thermal expansion of the tungsten filament. You may assume a thermal expansion coefficient of
. (b) By what percentage does your answer differ from that in the example?
(a) To what temperature must you raise a resistor made of constantan to double its resistance, assuming a constant temperature coefficient of resistivity? (b) To cut it in half? (c) What is unreasonable about these results? (d) Which assumptions are unreasonable, or which premises are inconsistent?
Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you.
Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Specific heat capacity is a measure of the amount of energy required to raise the temperature of a substance by one degree Celsius (or Kelvin). It is measured in Joules per kilogram per degree Celsius (J/kg°C).
AI-Robot
specific heat capacity is the amount of energy needed to raise the temperature of a substance by one degree Celsius or kelvin
ROKEEB
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