Question 1 Two identical negative charges are located on the y-axis, at y = +4m and y = -4m. A positive charge of 0.25C is placed on the x-axis at x = 2m. What direction does the net force on the proton point? Select one: A. Along the -x-axis B. At a 45 degree angle […]

## Problem 20.57

In a simple model of the hydrogen atom, the electron moves in a circular orbit of radius 0.053nm around a stationary proton. Part A How many revolutions per second does the electron make? Hint: What must be true for a force that causes circular motion? Express your answer using two significant figures.

## Problem 20.36

Large electric fields in cell membranes cause ions to move through the cell wall. The field strength in a typical membrane is . Part A What is the magnitude of the force on a calcium ion with charge +e? Express your answer using two significant figures.

## Problem 20.10

A small metal sphere has a mass of 0.17 g and a charge of -21.0 nC . It is 10 cm directly above an identical sphere with the same charge. This lower sphere is fixed and cannot move. Part A What is the magnitude of the force between the spheres? Express your answer to two […]

## Problem 20.9

Two 2.0 kg masses are 4.0 m apart on a frictionless table. Each has 1.0 of charge. Part A What is the magnitude of the electric force on one of the masses? Express your answer using two significant figures. Part B What is the initial acceleration of each mass if they are released and allowed […]

## PSS 20.1: Electric forces and Coulomb’s law

Learning Goal: To practice Problem-Solving Strategy 20.1 Electric forces and Coulomb’s law. Two charged particles, with charges and , are located at a distance apart on the axis. A third charged particle, with charge , is placed on the axis such that the magnitude of the force that charge 1 exerts on charge 3 is […]