Multiple-choice question, Electric field and potential

AI Thread Summary
The discussion revolves around the relationship between the charges on two positively charged metal spheres connected by a conducting wire. When the wire is connected, the potentials of both spheres equalize due to the conductive nature of the wire, leading to the equation q1/q2 = a/b, where a and b are the radii of spheres A and B, respectively. The potential for each sphere is given by V = q/(4∏εr), confirming that the charges are proportional to their radii. The discussion also raises questions about the behavior of charges if the wire is cut and reconnected after altering the charges on the spheres. Ultimately, the key takeaway is that the conducting wire maintains equal potential between the spheres, regardless of their individual charges.
goodstudent
Messages
2
Reaction score
0
A positively-charged metal sphere A of reaius a is jointed by a long conducting wire to another positively charged metal sphere B of radius b. Assume that B is far away from A. If the charges on A and B are respectively q1 and q2, what is the ratio q1:q2?

Relevant equations
V=q/(4∏εr)

a) a^2:b^2
b) a:b
c) b^2:a^2
d) b:a

Solution:
The conducting wire ensures that the potentials of the two spheres are the same. Since they are far apart, the charge of any sphere will not influence the potential of one another.
V(sphere a)=V(sphere b)
q1/(4∏εa) = q2/(4∏εb)
∴ q1/q2=a/b
This is the solution from the book.
Why the potentials of the two sphere are the same when they joined by a conducting wire?
 
Physics news on Phys.org
Suppose you

- Cut the wire somewhere between the spheres,
- Put a charge on the spheres such that two spheres have different potentials, and
- Reattach the cut ends of the wire.

What flows down the wire?
 
The charges in the sphere?
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Confusion on the distribution of charge
Replies
7
Views
2K
Charge on a grounded conducting sphere in a uniform electric field, after ungrounding and movement
Replies
1
Views
1K
Electrostatics help please -- Electric field, potential
Replies
5
Views
2K
Induced charge on a conducting sphere sliced by a plane
Replies
2
Views
1K
Electric field external to Conducting Hollow Sphere with charge inside
Replies
23
Views
3K
Gauss' Law question about a conducting rod
Replies
3
Views
2K
Capacitors, equipotentials, and electric fields
Replies
5
Views
954
Electric Potential and Field Diagram - True/False
Replies
6
Views
2K
What does having 3d symmetry 2d symmetry and 1d symmetry mean?
Replies
36
Views
2K
Electric potential inside a shell of charge
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top