Resistance and Variation of Current in a Gradually Narrowing Ohmic Wire

In summary, the conversation discusses how the current varies along a current-carrying ohmic metal wire with a decreasing cross-sectional area. The question presented is whether the current increases, remains constant, or decreases along the length of the wire. The correct answer is that the current remains constant, while the resistivity of the wire increases. There is also a clarification about the possible intention of the question, which could be asking about the variation of drift speed or resistance along the wire.
  • #1
bennyq
23
0

Homework Statement



A current-carrying ohmic metal wire has a cross-sectional area that gradually becomes smaller from one end of the wire to the other. How does the current vary along the length of the wire?

Homework Equations



a. It increases.
b. It remains constant.
c. It decreases.


The answer give is (A).. I am a bit confused, as my understanding is the resistance will increase in the wire, but the current should be constant through it as to not accumulate any charge in the wire.. So the wires resistance increases, and the drift speed of the electrons increase to maintain the constant current through the wire?? Do you think the questions is meant to ask, how does the driftspeed/resistance vary along the length?
 
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  • #2
You are right, the current is the same along the wire. The resistivity increases.

ehild
 

What is resistance?

Resistance is the measure of how much a material or device impedes the flow of electric current. It is measured in ohms (Ω) and is influenced by factors such as the material's composition, length, and thickness.

What is the relationship between resistance and current flow?

According to Ohm's Law, there is an inverse relationship between resistance and current flow. This means that as resistance increases, current flow decreases, and vice versa. This relationship is represented by the equation: R = V/I, where R is resistance, V is voltage, and I is current.

How does temperature affect resistance?

Temperature can affect resistance in different ways depending on the material. In most materials, as temperature increases, resistance also increases. However, in some materials like semiconductors, resistance decreases with increasing temperature.

What is the difference between AC and DC current flow?

AC (alternating current) and DC (direct current) are two types of electric current flow. DC current flows in one direction at a constant rate, while AC current alternates direction at a specific frequency. In terms of resistance, AC current can be affected by the inductance and capacitance of a circuit, while DC current is not influenced by these factors.

How can resistance be reduced in a circuit?

Resistance can be reduced in a circuit by increasing the diameter of the wire, which allows for more space for the electrons to flow. Additionally, using materials with lower resistivity, such as copper, can also decrease resistance. Lastly, reducing the length of the wire can also decrease resistance as there is less distance for the electrons to travel.

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