Electric Charges and Fields - Online Test
Q1. A point charge q = -8.0 nC is located at the origin. Magnitude of the electric field vector at the field point x = 0.949m y = -1.643m is
Answer : Option C
Explaination / Solution:
Given x= 0.949m and y= -1.643 m So
Q2. If two electrons are each 1.50× 10-10 m from a proton, as shown in Figure , magnitude of the net electric force they will exert on the proton is
Answer : Option A
Explaination / Solution:
Putting the value of We have
Putting the value of We have
Q3. A point charge Q is moved along a circular path around another fixed point charge The work done is zero
Answer : Option C
Explaination / Solution:
Since that circular path behave as equipotential surface so work done is always zero.
Q4. In a regular polygon of n sides, each corner is at a distance of r from the center. Identical charges of magnitude Q are placed at (n -1) corners. The field at the center is
Answer : Option D
Explaination / Solution:
If the same charges are placed at all corners on polygon than the electric field at centre will be zero, but in given situation one charge is missing , so the field at the centre now become non zero and the net field at centre must be equal to the field which the missing charge exert such that the total field become zero So now the field at centre=field due to missing charge =
Q5. Which of the following is not true for a region with uniform electric field?
Answer : Option B
Explaination / Solution:
In each of the cases given the electric field is not uniform.
Q6. A charge Q is placed at the mouth of a conical flask. The flux of the electric field through the flask is
Answer : Option A
Explaination / Solution:
If the charge enclosed by conical flask than the flux is
But the charge is placed at the mouth of flask so if we draw another imaginary flask over it the charge is surrounded by two flasks now so the charge through the flask now half of the previous value (shared by two flask) So
Q7. A long string of charge λ per unit length passes through an imaginary cube of edge a. The maximum flux of the electric field will be
Answer : Option D
Explaination / Solution:
The maximum length of string that can be fit into cube is
which is equal to the length of body diagonal So the charge inside the cube is
So flux
