The oscillatory contour consists of the coil of inductance and the condenser which are connected in a uniform chain. Each coil has inductance, and the condenser electric capacitance. Frequency of fluctuations which can be received in a contour also depends on these sizes.
It is required to you
- — oscillatory contour;
- — set of coils of inductance;
- — air condenser;
- — condenser with replaceable electric capacitance.
Instruction
1. To change frequency at first find its value, using Thomson's formula. It shows dependence of the period of fluctuations of a contour of T on its inductance of L and electric capacitances of C. The period of fluctuations is equal to the work of number 2 on π ≈ 3.14 and a root square of the work of inductance on electric capacitance T=2 ∙π ∙√ (L∙C). As frequency ν is a size inversely proportional to the period that it is equal ν=1 / (2 ∙π ∙√ (L∙C)).
2. Increase inductance of the coil of an oscillatory contour. Frequency of fluctuations will decrease. Reduce inductance of the coil and frequency will increase. Change of frequency will happen in so many time how much to change inductance, but take a square root from this number. For example, if to reduce inductance of an oscillatory contour by 9 times, its frequency will increase by 3 times.
3. To change inductance of the coil, change quantity of rounds of the coil. Consider that change of quantity of rounds in n of times inductance to change in n². For example, if in a contour there was a coil of 1200 rounds, and instead of it to install the coil of 3600 rounds with the same section and the core, then the quantity of rounds will increase by 3 times, and the inductance will increase by 9 times. For change of inductance in proportion change the area of the core of the coil.
4. If to increase electric capacitance, then frequency will decrease in so many time when the electric capacitance increased, but take a square root from this number. For example, increase electric capacitance by 25 times, receive reduction of frequency by 5 times. Reduction of electric capacitance will give increase in frequency by the same principle.
5. For change electric capacitance just replace the condenser. If the condenser air, increase the area of its plates, or reduce distance between them, or bring between plates dielectric with bigger dielectric permeability. Depending on change of each of sizes the electric capacitance will change in proportion. For example, having increased the area of plates by 3 times, having reduced distance between plates twice, and having brought between them a paraffin plate with relative dielectric permeability 3, we will receive change electric capacitance of 3∙2∙3=18 times.