Question

Jorge wanted to find out how many 9-volt batteries connected in a series are required to create a 120-volt circuit. So, he divided 120 by 9 and concluded that he needed 13 1/3. Write a sentence explaining Jorge's mistake, and tell the correct answer

Answer 1

Jorge would need over 13
`(1)/(3)` number of 9 volts battery to create 120 volts.

Step-by-step explanation:

A series connecting is one in which two or more batteries are connected terminal-to-terminal, so that the same current flow through each battery. Each battery has an internal resistance, r, which is the opposition to the flow of current by the battery itself.

The total emf, E, of a given number of cells connected in series is given by;

E =
`E_(1)` +
`E_(2)` +
`E_(3)` +
`E_(4)` + .........

And each of the cell has an internal resistance, r. So that the total internal resistance of the cells in series is;

r =
`r_(1)` +
`r_(2)` +
`r_(3)` +
`r_(4)` + .......

Thus, Jorge's mistake was that 13
`(1)/(3)` number of 9 volts batteries would not give 120 volts because each battery has its internal resistance. Therefore the appropriate answer is that he would need over 13
`(1)/(3)` number of 9 volts battery to create 120 volts.