Potential Difference and Current

In summary, the discussion is about two identical wires made of different materials, connected in series and connected to a battery. The resistivity and resistance of the wires change, but the potential difference remains the same. The current in both wires must also be the same due to the rule that series connected components carry the same current.
  • #1
bbuilder
14
0

Homework Statement



Wires 1 and 2 are identical except that they are each made of a different material. The one end of wire 1 is connected to one end of wire 2. The two remaining ends are connected across a battery and current flows through the two wires. Is the potential difference is wires 1 and 2 the same or different? Is the current in wires 1 or 2 the same or different?

Homework Equations



R=(ρL)/A
V=IR

The Attempt at a Solution


The resistivity would change because the material changes; therefore, the resistance changes. If the resistance changes, the current changes. Potential difference remains the same. Is this correct?
 
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  • #2
Think about this, if you have two wires connected in series but they don't have the same current flowing through them, what happens at the point where they meet? If the current is higher in the first wire? In the second?
 
  • #3
If the current is higher in the first wire, then the first wire must have a lower resistance. If the current is lower in the first wire, then the first wire must have a higher resistance.
 
  • #4
bbuilder said:

The Attempt at a Solution


The resistivity would change because the material changes; therefore, the resistance changes. If the resistance changes, the current changes. Potential difference remains the same. Is this correct?

If current were to be different in the two segments, wouldn't you end up with some continuous positive or negative charge building up where they connect? How could a continuous buildup of charge be sustained without catastrophic consequences?

The rule is, series connected components (including wires) carry the same current; What goes in one end of a wire must come out at the other end at the same rate.

If the wires have different resistivities, and hence difference resistances, you should be able to consult Ohm's law to see how the potential differences across the individual wire segments will behave, given that both segments MUST carry the same current.
 
  • #5
If it were true the current would change, I wouldn't have to pay for electricity, sadly it doesn't work like that :( Something does change, but it is not the current. In a series connection, say you have some consumers A B C with resistances, how would you calculate the total voltage in the series?
 

FAQ: Potential Difference and Current

What is potential difference?

Potential difference, also known as voltage, is the difference in electrical potential energy between two points in an electrical circuit. It is measured in volts (V) and is responsible for the flow of current.

What factors affect potential difference?

The two main factors that affect potential difference are the amount of charge and the distance between two points in a circuit. The greater the amount of charge, the greater the potential difference. Similarly, the greater the distance between two points, the greater the potential difference.

What is current?

Current is the rate of flow of electric charge through a conductor. It is measured in amperes (A) and is dependent on the potential difference and the resistance of the conductor. It is represented by the symbol "I" and flows from the positive terminal to the negative terminal in a circuit.

What is the relationship between potential difference and current?

The relationship between potential difference and current is described by Ohm's Law, which states that the current flowing through a conductor is directly proportional to the potential difference applied across it, as long as the temperature and other physical conditions remain constant. This relationship can be represented by the equation I = V/R, where I is the current, V is the potential difference, and R is the resistance of the conductor.

How are potential difference and current measured?

Potential difference is measured using a voltmeter, which is connected in parallel to the circuit. Current is measured using an ammeter, which is connected in series to the circuit. Both of these instruments are calibrated to display their respective measurements in volts and amperes.

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