What are the magnitude and direction of the electric field at the dot?

What are the strength and direction of an electric field that will balance the weight of (a) a proton and (b) an electron?

Determine the magnitude and direction of the electric field at a point midway between a $-4~\text{nC}$ and a $23 ~\text{μC}$ charge $10~\text{cm}$ apart.

What are the magnitude and the direction of the electric field that will balance the weight of an electron? What are the magnitude and direction of the electric field that will balance the weight of a proton?

A Van de Graaff generator is charged so that the magnitude of the electric field at its surface is $3.0 \times 10^{4}$ N/C. a. What is the magnitude of the electric force on a proton released at the surface of the generator? b. Find the proton’s acceleration at this instant.

The metal spheres in figure mentioned are charged to $\pm 300 \mathrm{~V}$. Draw this figure on your paper, then draw a plausible contour map of the potential, showing and labeling the $-300 \mathrm{~V}$, $-200 \mathrm{~V},-100 \mathrm{~V}, \ldots, 300 \mathrm{~V}$ equipotential surfaces.

Determine the magnitude and direction of the electric force on an electron in a uniform electric field of strength $2460 \mathrm{~N} / \mathrm{C}$ that points due east.

A coaxial cable consists of a wire of radius a surrounded by a thin metal cylindrical shell of radius b. The wire has a uniform linear charge density $\lambda > 0$ and the outer shell has a uniform linear charge density $-\lambda$. (a) Sketch the field lines for the cable. (b) Find expressions for the magnitude of the electric field in the regions $r \leq a , a < r < b$, and $b \leq r$.

A long coaxial cable consists of an inner cylindrical conductor with radius a and an outer coaxial cylinder with inner radius b and outer radius c. The outer cylinder is mounted on insulating supports and has no net charge. The inner cylinder has a uniform positive charge per unit length $\lambda$. Calculate the electric field at any point between the cylinders a distance r from the axis and

Two flat, parallel electrodes 2.5 cm apart are kept at potentials of 20 V and 35 V. Estimate the electric field strength between them.

In proton beam therapy, a beam of high-energy protons is Blu is used to deliver radiation to a tumor, killing its cancerous cells. In one session, the radiologist calls for a dose of $4.9 \times 10^8$ protons to be delivered at a beam current of $120 \mathrm{nA}$. How long should the beam be turned on to deliver this dose?

What is the potential difference between $x_{i}=10 \mathrm{cm} \text { and } x_{i}=30 cm$ $E_{x}=1000 \mathrm{V} / \mathrm{m}$?

An electron moving through an electric field experiences an acceleration of $6.3 \times 10^{3} \mathrm{m} / \mathrm{s}^{2}$. Find the electric force acting on the electron.

Figure mentioned is a graph of $E_{x^*}$. What is the potential difference between $x_1=1.0 \mathrm{~m}$ and $x_{\mathrm{f}}=3.0 \mathrm{~m}$ ?