Practice Test 1

A fixed source charge $-Q$ is at the origin. Point $P$ lies on the $+x$ axis. A small positive test charge $+q$ is placed at $P$ only to sense the field. Which statement best describes the direction of the electric field at $P$ due to the source charge?

A fixed source charge $+2Q$ is at the origin. Point $A$ is at distance $r$ from the origin, and point $B$ is at distance $2r$. A small test charge is used only to measure the field. Compared to the electric field magnitude at $B$, the electric field magnitude at $A$ is