This paper reports on the measurement of a magnetic field due to the coil carrying current by using the magnetic sensor in a smartphone as an alternate to the relatively expensive magnetic sensor probe. The location of the magnetic sensor in the smartphone was known by mapping the value of the magnetic field due to the permanent magnetic bar so that we could obtain an accurate measurement. The variable parameter examined in this magnetostatics experiment was the distance of coils to the magnetic sensor in a smartphone and the magnitude of the current in the coils. The coils used in this research have 8 cm radii and 30 turns of wire, with a 0.3 A current flowing, and the coils were arranged to make a Helmholtz and anti-Helmholtz configuration. The resulting magnetic fields by a coil, Helmholtz coil and anti-Helmholtz coil were measured and compared with the value from calculations using an analytical and numerical approach. According to these results, it can be confirmed that the magnetic field due to a Helmholtz and anti-Helmholtz coil can be measured accurately using the smartphone's magnetic sensor in a physics experiment.
The present work reports the influence of TiO 2 /Ag particles on the properties of chitosan film. Pure chitosan film and TiO 2 /Ag-chitosan composite film were prepared by solution casting method with wet phase separation from the glass substrate. Potassium hydroxide (KOH) solution was used to produce flexible free-standing films. Field emission scanning electron microscopy (FE-SEM) image shows that morphology structure of TiO 2 /Ag-chitosan composite film is rough and heterogeneous. UV-vis spectra show the red-shifted absorption band of TiO 2 /Ag-chitosan film due to particle agglomeration in the chitosan polymer. The addition of TiO 2 /Ag decreases the band-gap energy of chitosan from 5.2 to 4.7 eV because TiO 2 /Ag particles altered chitosan energy states that is appropriate to x-ray diffraction (XRD) results. The Fourier transform infrared (FTIR) spectra confirm only physical interaction between TiO 2 /Ag and chitosan, without any chemical reaction happening. The addition of TiO 2 /Ag particles to the chitosan reduced the plasticising or elasticity of chitosan film because of the agglomeration.
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