Calculating Charge and Current in a Resistor Circuit

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Homework Help Overview

The discussion revolves around calculating the charge that has passed through a resistor connected to a battery over a specified time period. The circuit consists of a 23 ohm resistor and a 4.4V battery, raising questions about current and charge relationships.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants explore the relationship between voltage, current, and charge, with some attempting to apply formulas such as Q = CΔV and I = ΔV/R. Questions arise regarding the correct application of these formulas and the nature of current in the circuit.

Discussion Status

There is an ongoing examination of whether the current is constant in the circuit. Some participants assert that it is constant, while others express confusion and question the assumptions made about the circuit's components. Clarifications are being sought regarding the application of charge and current equations.

Contextual Notes

Participants note the absence of capacitors in the problem, which influences their understanding of current behavior in the circuit. There is also a discrepancy in the resistor value mentioned in calculations, leading to further questioning of the setup.

whitehorsey
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1. At time t = 0, a 23 ohms resistor is linked to a 4.4V battery. How much charge has gone through the resistor after 5 seconds?

2. Q = CΔV
ΔV = IR

3. ΔV = IR
I = ΔV/R
= 4.4/24 A.

I'm not sure what to do next.
 
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whitehorsey said:
1. At time t = 0, a 23 ohms resistor is linked to a 4.4V battery. How much charge has gone through the resistor after 5 seconds?

2. Q = CΔV
ΔV = IR

3. ΔV = IR
I = ΔV/R
= 4.4/24 A.

I'm not sure what to do next.

Q = ∫I dt
 
whitehorsey said:
1. At time t = 0, a 23 ohms resistor is linked to a 4.4V battery. How much charge has gone through the resistor after 5 seconds?

2. Q = CΔV
ΔV = IR

3. ΔV = IR
I = ΔV/R
= 4.4/24 A.

I'm not sure what to do next.

How did the 23Ω become a 24 when you wrote it down in the formula?

Anyway, what is the relationship between a constant current, charge and time?
 
Note that the current is not constant in this case!
 
vanhees71 said:
Note that the current is not constant in this case!

EDIT: At first, I thought I'd made a ghastly mistake because I'd forgotten a capacitor or something. But this is just a simple circuit with a battery and a resistor. Why can't the current be assumed to be constant?
 
vanhees71 said:
Note that the current is not constant in this case!

There is only a resistor and a battery, how is the current not constant?
There is no indication of capacitance in the question details.
 
The current is constaant. Find the current and find that charge using the time given. Straight foward!
 
Ok, then I didn't understand the question. I thought there is a resistor and a capacitor. So the Q=CU equation doesn't make any sense.
 
whitehorsey said:
1. At time t = 0, a 23 ohms resistor is linked to a 4.4V battery. How much charge has gone through the resistor after 5 seconds?

2. Q = CΔV
ΔV = IR

3. ΔV = IR
I = ΔV/R
= 4.4/24 A.

I'm not sure what to do next.

1 A = ?? coulombs/sec
 
  • #10
I figured it out. Thanks guys!
 

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