State one shared feature and one difference between the electric field lines and the gravitational field lines around an isolated positively charged metal sphere.
A positive point charge $+Q$ is placed at a fixed point $X$ and an identical positive point charge is placed at a fixed point $Y$, as illustrated in Fig. 6.1. The charges are in a vacuum and are $10.0\ \text{cm}$ apart. Points $A$ and $B$ lie on the line $XY$. Point $A$ is $2.5\ \text{cm}$ from $X$ and point $B$ is $2.5\ \text{cm}$ from $Y$. The electric field strength at point $A$ is $4.1 \times 10^{-5}\ \text{V m}^{-1}$.
Calculate the value of charge $+Q$.
On Fig. 6.2, sketch how the electric field strength $E$ varies with distance $d$ from $A$ to $B$, along the line $AB$.
A small positive charge is placed at $A$. The electric field causes this charge to move from rest along the line $AB$. Describe the acceleration of the charge as it moves from $A$ to $B$.
On Fig. 6.2, sketch how the electric field strength $E$ varies with distance $d$ from A to B, along the line AB.
A small positive charge is placed at A. The electric field makes this charge start from rest and travel along the line AB. Describe how the acceleration changes as the charge moves from A to B.