Resistances in Series, Parallel, and Series-Parallel Combinations

[predentalgirl1]

A 120-V circuit has a circuit breaker rated to trip (to create an open circuit) at 15 A. How many 300-ohm resistors could be connected in parallel without tripping the breaker?








Given that,
V= 120V, I = 15A, R= 300 ohm.
Let the total resistance without tripping the breaker = Rp
Now 1/Rp = 1/R + 1/ R + ………n times.
= n/R
Therefore Rp = R/n
Or n = R/ Rp
But Rp = 120/15
= 8
Therefore n = 300/8
= 37.5=38

Is this correct?

 

[Mindscrape]

No, because it will break on the 38th resistor. You want the one before **** hits the fan, the one right before the circuit breaks.