Describe the behavior of parallel conductors with currents in opposite directions and waves moving from deep to shallow medium.

Here are the solutions to the questions:

9)

i) When currents flow in opposite directions in parallel conductors, the conductors repel each other.

• For conductor A, the force $\text{F}$ will be directed to the left (away from B).
• For conductor B, the force $\text{F}$ will be directed to the right (away from A).

\begin{tikzpicture}[scale=0.8] % Conductor A \draw (0,0) circle (0.5); \node at (0,0) {$\odot$}; % Current out of page \node at (0,1) {A}; % Conductor B \draw (4,0) circle (0.5); \node at (4,0) {$\otimes$}; % Current into page \node at (4,1) {B}; % Magnetic field lines (simplified representation for repulsion) \draw[->] (2, -2) arc (-90:90:2 and 2); \draw[->] (2, 2) arc (90:270:2 and 2); % Forces \draw[->, thick, red] (0,0) -- (-1,0); \node[red] at (-1.3,0) {F}; \draw[->, thick, red] (4,0) -- (5,0); \node[red] at (5.3,0) {F}; \end{tikzpicture}

10)
When waves travel from a deep to a shallow medium, their speed decreases, and their wavelength decreases. If they approach the boundary at an angle, they also refract (bend) towards the normal. The wave crests in the shallow medium will be closer together and bent.

\begin{tikzpicture}[scale=0.8] % Deep medium waves \foreach \x in {-2,-1,0,1,2} { \draw (\x, -2) -- (\x, 2); } \draw[->] (0.5, 0) -- (1.5, 0); % Direction of propagation \node at (0, -2.5) {Deep}; % Boundary \draw[thick] (2,-2) -- (4,2); \node at (4.5, 2.5) {Shallow}; % Shallow medium waves (refracted and shorter wavelength) \draw (2.2, -1.8) -- (3.2, 0.2); \draw (2.4, -1.4) -- (3.4, 0.6); \draw (2.6, -1.0) -- (3.6, 1.0); \draw (2.8, -0.6) -- (3.8, 1.4); \draw (3.0, -0.2) -- (4.0, 1.8); \end{tikzpicture}

Radioactive decay question (unnumbered):