The given diagram indicates the energy levels of a certain atom. When the system moves from level to — Atomic Structure Chemistry Question

Question

The given diagram indicates the energy levels of a certain atom. When the system moves from $2E$ level to $E$ level, a photon of wavelength $\lambda$ is emitted. The wavelength of the photon emitted during its transition from $4E/3$ level to $E$ level is. [Diagram: Three energy levels at $2E$, $4E/3$, and $E$. Arrow from $2E$ to $E$ emits $\lambda$. Arrow from $4E/3$ to $E$ is unknown.]