# Physic

Two resistors when connected in series to a 120-V line use one-fourth the power that is used when they are connected in parallel. If one resistor is 4.8 kohms. what is the resistance of the other?

1. 👍
2. 👎
3. 👁
1. E = 120 V.
R1 = 4.8k
R2 = ?

R1+R2 = 4(R1*R2)/(R1+R2)
(R1+R2)^2 = 4(R1*R2)
R1^2+2R1*R2+R2^2 = 4R1*R2
23.04+9.6R2+R2^2 = 19.2R2
R2^2 - 9.6R2 + 23.04 = 0
R2 = 4.8k

Check:
Parallel Connection
P1 = E^2/2.4k = 120^2/2.4k = 6,000 mW = 6 W.

Series connection
P2 = 120^2/(4.8k+4.8k) = 1,500 mW = 1.5 W.

P2/P1 = 1.5/6 = 1/4

1. 👍
2. 👎

## Similar Questions

1. ### physics

A 30 ohm resistor is connected in parallel with a variable resistance R. The parallel combination is then connected in series with a 6 ohm resistor and connected across a 120 V source. Find the minimum value of R if the power

2. ### Physics

Thanks for any help :) Four 20 ohm resistors are connected in parallel and the combination is connected to a 20V emf device. The current is: A) 0.25A B) 1.0 A C) 4.0 A D) 5.0 A E) 100 E Parallel circuits: I know that the voltage

3. ### physics

two unknown resistors a and b are connected together. when they are connected in series their combined resistance is 15 ohm. When they are connected in parallel, their combined resistance is 3.3 ohm. What are the resistances of A

4. ### Physics

A circuit consisting of three resistance 12ohm, 18ohm and 36ohm respectively joined in parallel, and connected in series with the fourth resistance. The whole circuit is supplied at 60volts and it is found that the power

1. ### Physics

1)Four resistors of 10.0 each are connected in parallel. A combination of four resistors of 10.0 each is connected in series along with the parallel arrangement. What is the equivalent resistance of the circuit? A)80.0 B)40.4

2. ### physics

A 15.0 Ohms resistor is connected in series to a 120V generator and two 10.0 Ohms resistors that are connected in parallel to each other. -What is the total resistance of the load? -What is the magnitude of the circuit current?

3. ### Electrotechnics N4

A circuit,consisting of 3 resistances 12,18 & 36 ohms respectively joined in parallel is connected in series with fourth resistance.the whole is supplied at 60 volt & it is found that the power dissipated in the 12Ohm resistance

4. ### Physics Electric Circuits

3. A 15.0 ohm resistor is connected in series to a 120 V generator and two 10.0 ohm resistors that are connected in parallel to each other. b) What is the current through the 15.0 ohm resistor? c) What is the current through one

1. ### Physics ASAP!!

1. Three resistors are placed in series. They have the following resistances: R1 = 20 ohms, R2 = 20 ohms, R3 = 10 ohms. What current would be moved through this circuit by a 5-V power supply? A. 1.0 A B. 0.10 A C. 25 A D. 250 A 2.

2. ### physics

12.oo volt battery is connected in a series to 4 identical 5.00 ohm resistors what is the current

3. ### physics

A series circuit is formed with a 10-V power supply and two resistors, where R1 = 6 ohms and R2 = 4 ohms. The current through the resistors is I1 and I2, respectively. What are the values of I1 and I2? I1 = I2 = 1.0 A I1 = I2 =

4. ### physics

three resistors of 2ohm, 3ohm and 4 ohm are connected in (a) series (b) parallel. find the equivalent resistance in each case