# CIRCUITS

two resistors of 25 ohms and 5 ohms respectively are connected in series to a 240V supply calculate the value of a third resistor to be connected in parallel with 25 ohms resistor so that the power dissipated shall be tripled

1. 👍 0
2. 👎 0
3. 👁 97
1. For each branch, P = E^2/R

Currently (no pun intended), we are dissipating 240^2/(25+5) = 1920 watts

So, we want to dissipate 3840 watts in the other branch.

240^2/R = 3840
R = 15 ohms

1. 👍 0
2. 👎 0
posted by Steve
2. two resistors in series, 25,5 ohms.
power= 1920
want 240^2/(r'+5)=3840
figure r', then

1/r'=1/25+1/R
solve for R, the resistance going in parallel with the 25 ohm resistor

1. 👍 0
2. 👎 0
3. Go with bobpursley -- I misread the problem, connecting the parallel R across both series resistances.

1. 👍 0
2. 👎 0
posted by Steve
4. P = E^2/(R1+R2) = 240^2/(25+5) = 1920 Watts = Current power.

Rt = (25+5)/3 = 10 Ohms = Total resistance required to triple the power.

Rt = R1*R3/(R1+R3) + R2 = 10.
(25*R3)/(25+R3) + 5 = 10
25R3/(25+R3) = 5
25R3 = 125 + 5R3
R3 = 6.25 Ohms.

1. 👍 0
2. 👎 0
posted by Henry

## Similar Questions

1. ### Physics (URGENT)

Three wire-wound resistors have the following values: 30 ohms, 80 ohms, and 100 ohms. Each resistor has a voltage rating of 100V. If these three resistors are connected in series, can they be connected to a 240V circuit without

asked by Anonymous on September 24, 2013
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?

asked by Rony on February 17, 2010
3. ### Physics

For what combination of parallel and series resistors will resistors of 25 ohms, 100 ohms, 50 ohms, and 50 ohms have a total resistance of 62.5 ohms?

asked by Anonymous on May 12, 2018
4. ### Physics

A 5 ohms resistor is connected in parallel with the series assemvly of 2 ohms and 3 ohms resistors. The voltage drop across the 2 ohms resistor is 6V. What is the current through the 5 ohms resistor?

asked by Lyn on April 21, 2019
5. ### PHY [non-calc]

Resistors R1= 10ohms, R2= 40 ohms and R3= 70 ohms are connected in series. The total resistance in ohms of this combination is: A)0 B)120 C)28000 D) not enough info

asked by alice on May 31, 2011
6. ### Physics - Circuits

Theres a circuit wired in series that has 4 resistors. 1) 10 ohms 2) 6 ohms 3) 1 ohms 4) 2 ohms Find the potential difference across the 10ohm resistor. Answer in units of V What exactly am i supposed to do to calculate this?

asked by Anonymous on February 14, 2012
7. ### physics

Resistors R1, R2, and R3 have resistances of 15.0 Ohms, 9.0 Ohms and 8.0 Ohms respectively. R1 and R2 are connected in series, and their combination is in parallel with R3 to form a load across a 6.0-V battery. -What is the total

asked by Rony on February 18, 2010
8. ### Physics

I'm totally confused and this is due Monday- We're dealing with electrical circuits and I have to construct a circuit with resistors of 10 Ohms, 20 Ohms, 30 Ohms and 20 Ohms. The total resistance has to be 42 Ohms-Can someone

asked by Aubrey on March 26, 2011
9. ### College Physics

Two 9.1 ohms resistors are connected in parallel, as are two 5.9 ohms resistors. These two combinations are then connected in series in a circuit with a 20 V battery. What is the current in each resistor? I9.1, I5.9 = A What is

asked by Lanise on February 12, 2010
10. ### College physcs

Two 9.1 ohms resistors are connected in parallel, as are two 5.9 ohms resistors. These two combinations are then connected in series in a circuit with a 20 V battery. What is the current in each resistor? I9.1, I5.9 = A What is

asked by Lanise on February 10, 2010

More Similar Questions