The law of Ohm defines communication between tension, current and resistance of the conductor in an electrical circuit. Thus, using this law, it is possible to express tension on the site of a chain through its resistance.
It is required to you
- law of Ohm
Instruction
1. Let at a chain there is a site about R resistance. Then tension on this site of a chain in direct ratio to resistance on this site and is equal to U = to IR where I - current. It is also the law of Ohm. The law of Ohm for all chain can be written down in the form of E = (R+r) of I where E is the EMF of a source of tension, R is resistance of all external elements of a chain, and the internal resistance of a source of tension.
2. Resistance of the conductor can also be expressed through its characteristics on formula R =? *l/s. Here? - specific resistance of substance of the conductor (in the SI system unit of measure - Om*m), l - length of the conductor, and s - the area of its cross section. Then the formula for tension on the site of a chain will look so: U = I *?*l/s.
3. Let now on some site of a chain several resistors be connected consistently, and resistance of each resistor is equal to R1, R2..., Rn. The general resistance of the site of a chain will be equal to R = to R1+R2+...+Rn. Then tension on this site: U = I * (R1+R2+...+Rn). At parallel connection of resistors their general resistance is equal to R = 1 / (1/R1)+ (1/R2)+... + (1/Rn)). Tension on the site of a chain is equal to U = to I (1 / (1/R1)+ (1/R2)+... + (1/Rn))).