According to the law of Ohm to lower current in a chain, it is necessary to reduce potential difference (tension) on it or to increase resistance. The dependence at the same time is observed proportional - how much tension decreased, in so many time the current went down; on resistance inverse relation.
It is required to you
- tester, table of specific resistance.
Instruction
1. For reduction of current on the site of a chain change sizes on which it depends. To determine these sizes, use the equation which is one of types of record of the law of Ohm of I = U•S / (ρ\• l). Collect a chain, having attached a rheostat to the explored site. Connect it to a current source. After that, changing settings of a rheostat, reduce tension on the site. To receive tension indicators, attach a tester parallel to the site and perform measurement. Then, having attached a tester to the site consistently and having changed setting, measure current in a chain. Reduce tension on the site of a chain in n of times. Having measured current, make sure that it decreased in n of times too.
2. Change resistance of the site of a chain. For this purpose determine the specific resistance of material of conductors by the special table. For reduction of current pick up conductors of the same sizes, but with a big specific resistance. How much specific resistance will increase, in so many time the current will go down.
3. If there is no opportunity to pick up other conductors, change their geometrical sizes. Reduce the cross-sectional area of the conductor. For example, if a wire multicore, take away several veins. How much cross-sectional area will decrease, in as much time the current will go down. The second way is to increase the total length of conductors. How much length of conductors on the site of a chain will increase, in so many time the current will go down.
4. One more easy way is to attach a chain to a current source with smaller electromotive force. How much the EMF value will decrease, in so many time the current will decrease. These receptions can be combined for achievement of the best effect. For example, having lowered tension twice, having increased length of conductors 3 times and having reduced cross-sectional area by 4 times, you receive reduction of current by 2•3•4=24 times.