Barron's 2nd Edition DT Q46

Barron's Book

46) This question asks us to determine the electric field between two plates. We know the potential difference, the distance between the plates, and the charge of the plates. The first step is to set up a way to solve for the electric field using the values given to us.

Where V is potential difference, E is electric field, and r is distance

Many people will just plug in their values and forget about one crucial factor: the problem tells us the distance is 10 centimeters, but all the answer choices are given in volts per meter. This tells me that we need to convert the distance to meters before we plug in our values. It is extremely important to be aware of the units given and the units wanted in the answer. After we convert the units, we can quickly solve for the electric field.

Where E is electric field, V is potential difference, and r is distance

Answer: E