Electric Fields problem: Can someone please check my work?

AI Thread Summary
The discussion revolves around calculating the electric field at a point 4.0 cm to the left of a -3nC charge, with a +4nC charge located 6 cm to the right. The initial calculation yielded -14.75 nC, which was later corrected to +13275 N/C after addressing the direction of the electric fields from both charges. Participants confirmed the layout of the problem and clarified the correct units and direction for the electric field. The final answer was affirmed, emphasizing the importance of significant figures in the result. Overall, the calculations and understanding of electric field direction were validated.
goooogle
Messages
3
Reaction score
0
"a +4nC charge is 6/0 cm along a horizontal line toward the right of a -3nC charged object. Determine the E field at a point 4.0 cm to the left of the negative charge."

From what I understand, it goes Point ___ 4cm ____ (-3nC) _____ 6cm ____ (+4nC)

Using that, I got the answer to be -14.75 nC but I'm very unsure of myself. Can someone check?
 
Physics news on Phys.org
goooogle said:
"a +4nC charge is 6/0 cm along a horizontal line toward the right of a -3nC charged object. Determine the E field at a point 4.0 cm to the left of the negative charge."

From what I understand, it goes Point ___ 4cm ____ (-3nC) _____ 6cm ____ (+4nC)

Using that, I got the answer to be -14.75 nC but I'm very unsure of myself. Can someone check?
Hello goooogle. Welcome to PF !

You have the layout correct.

Can you explain how you got that answer?

For sure, the units are not correct.
 
SammyS said:
Hello goooogle. Welcome to PF !

You have the layout correct.

Can you explain how you got that answer?

For sure, the units are not correct.

Well, I did

((K)(-3 x10^-9))/(.04^2) + ((K)(4x10^-9)/(.1^2) which gets me -13275. From there, I did -13725 = ((K)(X))/(.1^2) which comes out to -14.75 nano coloumbs.

Is that right? Is .1 the right distance for the second part?
 
goooogle said:
Well, I did

((K)(-3 x10^-9))/(.04^2) + ((K)(4x10^-9)/(.1^2) which gets me -13275. From there, I did -13725 = ((K)(X))/(.1^2) which comes out to -14.75 nano coloumbs.

Is that right? Is .1 the right distance for the second part?
For the first part: What is the direction of the E-field due to the negative charge? What is the direction of the E-field due to the positive charge?

What are the units of the number -13275 ?What second part. You didn't mention a second part in the question.
 
SammyS said:
For the first part: What is the direction of the E-field due to the negative charge? What is the direction of the E-field due to the positive charge?

What are the units of the number -13275 ?What second part. You didn't mention a second part in the question.

The direction for the E-field because of the negative charge would be to the right, so +? In that case, it'd be 16875 - 3600, which is +13275. So I understand that, I think. The units are N/C. The second part was just desperation, trying to find a step I missed.

So I take it +13275 N/C is my final answer?
 
goooogle said:
The direction for the E-field because of the negative charge would be to the right, so +? In that case, it'd be 16875 - 3600, which is +13275. So I understand that, I think. The units are N/C. The second part was just desperation, trying to find a step I missed.

So I take it +13275 N/C is my final answer?
Your result looks okay for magnitude, units, and direction. Be sure to round any result that is to be presented as a final answer to the correct number of significant figures.
 
  • Like
Likes SammyS

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

Confused about direction of electric field
Replies
7
Views
3K
Why Is Work Positive When Done Against the Electric Field?
Replies
22
Views
3K
Find the electric field between 2 finite discs
Replies
16
Views
1K
Dipole placed in a uniform electric field
Replies
11
Views
3K
External forces required to move an electric dipole quasi-statically
Replies
14
Views
1K
Find the magnitude of the electric field at point P
Replies
5
Views
2K
I Thought I Understood Gauss' Law (Sheets)
Replies
26
Views
2K
Finding the electric field at point - Can someone check my work?
Replies
3
Views
1K
Electric field at a point problem
Replies
1
Views
2K
Calculating work done by an Electric field on a positive charge
Replies
4
Views
2K

Hot Threads

Recent Insights

Back
Top