Abstract:
Water is one of the most valuable natural resources subsequent to the air. The utilization
of water can’t be separated from the quality of the water, where poor water conditions are not
only an indicator of environmental damage, but also a threat to the ecosystem. One of indicator
water quality is determined by dissolved oxygen. In this research, an instrument to measure the
effect of dissolved oxygen was built based on the susceptibility value of a solution at low
frequencies of 1 Hz, 10 Hz and 100 Hz. The instrument used consists of 217 turns of the primary
coil and 30,000 turns of the secondary coil. A magnetic instrument with an RC circuit is designed
to produces a magnetic field, which can inspect sample solutions easily and simply. The RC circuit
used resistor and capacitor values of 1 MΩ and 10 μF, respectively, which produces a pole
frequency of 0.016 Hz. The gradient value of the measurement solution gets smaller when the
frequency is increased, the gradient value at the frequency of 1 Hz is greater than at the
frequencies of 10 Hz and 100 Hz. The addition of oxygen to main solution aims to produce
solutions with a concentration of 0%, 25%, 50%, 75% and 100%. The measurement results show
an effect of solution concentration change on the susceptibility value, the greater the concentration
of the solution, the susceptibility value increases. The instrument that is built can also detect
changes in the value of the gradient on variations in concentration, frequency and diameter
