Question

A glass rod that has been charged to +12 nC touches a metal sphere. Afterward, the rod’s charge is +8.0 nC.

a. What kind of charged particle was transferred between the rod and the sphere, and in which direction? That is, did it move from the rod to the sphere or from the sphere to the rod?

b. How many charged particles were transferred?

Short answer

a. The electrons move from metal sphere to glass rod.

b. $N=2.5\times {10}^{10}electrons$were transferred.

Step-by-step solution

Content Introduction

According to the principle of quantization Any body's charge is an integral multiple of the charge on the integral. Furthermore, when electrons are taken from a body, the body's negative charge is also lost. A body becomes positively charged as a result of this.

Explanation (part a)

We are given that the glass rod has a charge $+12nC$and after it touches the metal sphere the charge changes to $+8nC.$

So metal sphere charge is

$$\begin{gathered} Q=12nc-(+8nC) \\ Q=+4nC \end{gathered}$$

The sphere is positively charged because the sphere is charged to$+4nC$by the rod. The electrons removed from the sphere and this is the only way to make the sphere charged positively where protons could not be added to the sphere.

Explanation (part b)

We have calculated the charge on the sphere as $Q=+4nC$and we are given, $e=-1.6\times {10}^{-19}C$.

The charge of metal sphere equals the number of carriers N times the carrier which is $-e$for electrons and $+e$for protons.

$$\begin{gathered} N=\frac{Q}{e} \\ N=\frac{-4\times {10}^{-9}C}{-1.6\times {10}^{-19}C} \\ N=2.5\times {10}^{10}electrons \end{gathered}$$