• Support PF! Buy your school textbooks, materials and every day products Here!

Equipotential line and electric field

  • Thread starter Saitama
  • Start date
  • #1
3,812
92

Homework Statement


The equation of an equipotential line in an electric field is y=2x, then the electric field strength vector at (1,2) may be
a)4i+3j
b)4i+8j
c)8i+4j
d)-8i+4j


Homework Equations





The Attempt at a Solution


Since its an equipotential line, the electric field vector should perpendicular to this line. Therefore, the slope of line perpendicular to y=2x is -1/2. The equation should be y=[itex]\frac{-1}{2}[/itex]x+k, where k is any constant. Now i am stuck, can somebody help me proceed in the right direction?
 

Answers and Replies

  • #2
881
40
You cannot find the exact vector, as there can be many answers satisfying the given condition. But, you sure can check the options to see which of them would give you a vector perpendicular to y=2x :wink:

I believe the options were specifically made that way so that you can get the answer.
 
  • #3
3,812
92
You cannot find the exact vector, as there can be many answers satisfying the given condition. But, you sure can check the options to see which of them would give you a vector perpendicular to y=2x :wink:

I believe the options were specifically made that way so that you can get the answer.
Yes, many answers are possible.
How can i check that the vector is perpendicular to line y=2x?
 
  • #4
881
40
Yes, many answers are possible.
How can i check that the vector is perpendicular to line y=2x?
Check the slopes of the vectors!
 
  • #5
3,812
92
Check the slopes of the vectors!
Lol, then the answer is d), its slope is -1/2.
But then what's the use of (1,2)?

EDIT: Got it why the points are given. :)
 
Last edited:
  • #6
881
40
Lol, then the answer is d), its slope is -1/2.
But then what's the use of (1,2)?

EDIT: Got it why the points are given. :)
Good going! :approve:
 

Related Threads for: Equipotential line and electric field

Replies
1
Views
3K
Replies
12
Views
7K
Replies
6
Views
22K
Replies
9
Views
6K
Replies
3
Views
9K
Replies
3
Views
8K
Replies
3
Views
7K
  • Last Post
Replies
6
Views
7K
Top