Question

Part A

What is the direction of the electric field at the dot in the figure (Figure 1) ?

a) to the right

b) down

c) up

d) to the left

Part B

What is the magnitude of the electric field at the dot?

Express your answer to one significant figure and include the appropriate units.

Answer 1

Concepts and reason

The concepts used to solve this problem are electric field and the equipotential lines.

Initially find the magnitude of direction of the electric field at the dot by using the relation between the equipotential lines and the electric field lines. After that calculate the magnitude of the electric field at the dot by using the relation between the electric field and the potential difference between the plates of the capacitor

Fundamentals

The electric field defined as the region, which is surrounded all over the charged particle within another particle experiences the force.

The relation between the electric field and the potential difference between the plates of the capacitor is expressed as follows:

Here, E is the electric field, dV is the change in potential, and dx is the change in the distance.

(A)

The relation between the electric field and the potential difference between the plates of the capacitor is expressed as follows:

Here, from the above expression the direction of potential is against to the electric field strength

Thus, from the above provided figure, it can be concluded that the direction of potential is upward and hence the direction of the electric field is downwards.

(B)

The relation between the electric field and the potential difference between the plates of the capacitor is expressed as follows:

Substitute 200 V for dV and 1cm for dx in above equation as follows:

Here, negative sign indicates the direction of electric field. Therefore, the magnitude of the electric field at the dot is 20000 V/m.

Ans: Part A

The direction of the electric field at the dot is in downward direction.

Part B

The magnitude of the electric field at the dot is 20000 V/m.