Calculating Resistance for Charging a Battery Circuit Using Ohm's Law

AI Thread Summary
To charge a battery circuit at a current of 10mA, a resistor must be added in parallel with the diode. The user is uncertain about how to calculate the resistance needed and is considering using Ohm's Law (V=IR). They question whether the voltage drop across the resistor would be 3V, allowing the battery to maintain a 12V drop. Clarification and guidance on these calculations are sought. Accurate resistance calculation is essential for proper battery charging.
dancergirlie
Messages
194
Reaction score
0

Homework Statement



Make a modification so that the battery is charged by the DC supply at a current of 10mA

**See attached diagram**

Homework Equations





The Attempt at a Solution



Well I know that I would put in a resistor in parallel with the diode. However, I don't know how I would solve for the resistance.

I'm assuming that I would use Ohm's law:

V=IR where I=10mA, and I don't know what the voltage drop across the resistor would be... would it be 3V so that the battery drops 12 volts?

Any help would be great!
 

Attachments

  • Screen shot 2011-02-24 at 5.04.32 PM.png
    Screen shot 2011-02-24 at 5.04.32 PM.png
    9.9 KB · Views: 610
Physics news on Phys.org
dancergirlie said:

Homework Statement



Make a modification so that the battery is charged by the DC supply at a current of 10mA

**See attached diagram**

Homework Equations





The Attempt at a Solution



Well I know that I would put in a resistor in parallel with the diode. However, I don't know how I would solve for the resistance.

I'm assuming that I would use Ohm's law:

V=IR where I=10mA, and I don't know what the voltage drop across the resistor would be... would it be 3V so that the battery drops 12 volts?

Any help would be great!

Yes, that is correct.
 
thanks for confirming :D
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Ohm's Law - Finding Source Voltage
Replies
3
Views
1K
Mechanisms Involved When Charging a Battery
Replies
10
Views
1K
Circuit with potential difference across battery being zero?
Replies
3
Views
1K
Why do the headlights on the car become dim when the car is starting?
Replies
4
Views
2K
Current through a circuit when the key is open
Replies
42
Views
5K
Homework help : The difference between these 2 circuits
Replies
16
Views
1K
Optimum Battery (and Wire) to Power 10x Mini 1.5V Bulbs in Parallel?
Replies
6
Views
2K
Voltage-resistance graph for this circuit with a variable resistance
Replies
4
Views
628
Introduce a battery to an LR circuit
Replies
16
Views
965
Electric Potential across charging battery.
Replies
5
Views
1K

Hot Threads

Recent Insights

Back
Top