Question

What is the equivalent resistance of a circuit that contains four 75.0 resistors connected in parallel with a 100.0 V battery?

A. 18.8

B. 175.0

C. 300.0

D. 5.32

Answer 1

To get the total resistance in a parallel circuit, you need to remember that unlike in a series, you do not just merely add the resistances. You need to get the reciprocal first of each resistance and add them together.


`(1)/(R_(T)) = (1)/(R_(1))+(1)/(R_(2))+(1)/(R_(3))... +(1)/(R_(n))`

After adding them, you will get the reciprocal again and then compute for the value. The problem says that there are 4 resistors in the circuit that have a resistance of 75.


`(1)/(R_(T)) = (1)/(75)+(1)/(75)+(1)/(75)+(1)/(75)`

Add up the numerator and copy the denominator:


`(1)/(R_(T)) = (4)/(75)`

Then get the reciprocal to get the total resistance:


`R _(T) = (75)/(4) = 18.75`

The answer to your question then is A. 18.8.