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We present here a set of simple experiments through which various characteristics of a DC motor can be investigated. The experiments also provide insights on how to control a DC motor. We first study the back-emf versus angular speed and the torque versus current characteristics. We then extract the moment of inertia of the rotor and the speedtorque curve for the load from the start-stop dynamics of the motor. Finally, we study an alternate way of obtaining the angular speed from the back-emf waveform.

Gated avalanche photo-detectors (GAPD) use gated detection and thresholding electronics to act as Geiger counters to indicate presence of photons. They show stationary Poissonian average noise statistics, though we see evidence of underlying non-stationary stochastic resonance. Both the Poissonian and stochastic resonance processes contribute to the experimentally observed dark count, and are described theoretically. To resolve photon numbers from coherent faint light pulses, we use GAPD with an optical recirculating loop. With the temporal separation of the input photons from the pulse, we not only achieve photon number resolution up to n = 0.024, but also bypass the stochastic resonance effects.

The ability to transport energy is a fundamental property of the two-dimensional Dirac fermions in graphene. Electronic thermal transport in this system is relatively unexplored and is expected to show unique fundamental properties and to play an important role in future applications of graphene, including opto-electronics, plasmonics, and ultra-sensitive bolometry. Here we present measurements of bipolar, electron-diffusion and electron-phonon thermal conductances, and infer the electronic specific heat, with a minimum value of 10 $k_{\rm{B}}$ ($10^{-22}$ JK$^{-1}$) per square micron. We test the validity of the Wiedemann-Franz law and find the Lorenz number equals $1.32\times(\pi^2/3)(k_{\rm{B}}/e)^2$. The electron-phonon thermal conductance has a temperature power law $T^2$ at high doping levels, and the coupling parameter is consistent with recent theory, indicating its enhancement by impurity scattering. We demonstrate control of the thermal conductance by electrical gating and by suppressing the diffusion channel using superconducting electrodes, which sets the stage for future graphene-based single microwave photon detection.