Resistances in Series, Parallel, and Series-Parallel Combinations

In summary, resistances in series are connected one after the other, while resistances in parallel are connected side by side. The total resistance in a series circuit is the sum of all individual resistances, while in a parallel circuit, it is calculated using the reciprocal formula. In a series-parallel combination, the total resistance is lower than in a purely series or parallel circuit. These combinations are commonly used in electronic circuits to improve efficiency and safety.
  • #1
predentalgirl1
67
1
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?
 
Physics news on Phys.org
  • #2
No, because it will break on the 38th resistor. You want the one before **** hits the fan, the one right before the circuit breaks.
 

Related to Resistances in Series, Parallel, and Series-Parallel Combinations

1. What is the difference between resistances in series and parallel?

In a series circuit, resistances are connected one after the other, resulting in a single path for the current to flow through. In a parallel circuit, resistances are connected side by side, providing multiple paths for the current to flow through.

2. How do you calculate the total resistance in a series circuit?

The total resistance in a series circuit is equal to the sum of all the individual resistances. This can be represented by the formula: Rtotal = R1 + R2 + R3 + ...

3. How do you calculate the total resistance in a parallel circuit?

The total resistance in a parallel circuit is calculated using the formula: 1/Rtotal = 1/R1 + 1/R2 + 1/R3 + ... This means that the total resistance is equal to the reciprocal of the sum of the reciprocals of all the individual resistances.

4. What happens to the total resistance when resistances are connected in series-parallel combination?

In a series-parallel combination, some resistances are connected in series and others are connected in parallel. The total resistance in this case is calculated by first finding the total resistance of the resistances connected in series, and then using that total resistance in the formula for parallel resistances. This results in a lower total resistance compared to a purely series or parallel circuit.

5. What is the significance of resistances in series-parallel circuits in real-life applications?

Resistances in series-parallel combinations are commonly used in electronic circuits, such as in household appliances and electronic devices. They allow for efficient use of resistors and can help manage the flow of current in a circuit, making it safer and more reliable.

Similar threads

  • Introductory Physics Homework Help
Replies
6
Views
580
  • Introductory Physics Homework Help
2
Replies
42
Views
2K
  • Introductory Physics Homework Help
Replies
7
Views
698
  • Introductory Physics Homework Help
Replies
3
Views
703
  • Electrical Engineering
Replies
2
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
966
  • Introductory Physics Homework Help
Replies
1
Views
896
  • Introductory Physics Homework Help
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
1K
Back
Top