Instruction

1

No matter what parameters are given in the problem statement, convert them to SI units.

2

If in the condition of the load resistance and allocated to her power, be guided by the following considerations:R=U/I where R is the resistance in Ohms, U - voltage, I - current intensity, A. P=UI, where P is power, W, U -

**drop****voltage**, I - current intensity, A. it follows that P=I^2*R, i.e., I^2=P/R, or I=sqrt(P/R). Hence, U=R(sqrt(P/R)) or, after simplifying the expression, U=sqrt(P)*sqrt(R), where U is the required**drop in****voltage**across the load, R is the resistance in Ohms, P is power, W.3

A much more simple case occurs if to find

**the drop in**voltage is required, knowing the power and strength of the current. To convert the expression does not need, so I use the following formula: U=P/I,where U is the required**drop in****voltage**In P power allocated to the load, W, I is the current passing through the load A.4

If you know the load resistance and passing through it a current,

**drop****the voltage**on it also calculate in one step:U=IR where U is the required**drop in****voltage**, I - current flowing through the load, And R is the load resistance in Ohms.5

In addition to the above the most common tasks in the textbooks there are also other that need to know

**the drop****voltage**on a segment of a long homogeneous rod, made of a material having a high resistance. To do this, first calculate the**drop****voltage**throughout the length of the rod (if it's not given in the problem statement initially). Then subtract from each other the horizontal coordinates of the points,**the drop****of voltage**between which is to be determined.6

The voltage on the entire length of the rod divide by its length, then multiply by your calculated length and you will get a

**drop in****voltage**between the points. Such dividers are found in the instrument with a transformerless power supply and are used as network switches**of the voltage**- in this case, the simplicity of the design is sacrificed to efficiency and safety.7

After completing the calculation, if necessary, translate the result into convenient for presentation units: volts, millivolts, kilovolts, etc.