# plz... solve Q27

### Asked by araima2001 | 18th Jul, 2017, 05:29: AM

###
-Convert the internal triangular network of resistors DEF from delta to star.

-As all the resistors of DEF are same i.e 1 ohm, the resistances of the star connection is (1x1)/(1+1+1)=1/3 ohm.

-Now these star resistors are connected in series with the 2 ohm resistors shown in the diagram with your question between AD, BE and FC.

-Therefore, the original network will now be reduced to the outward triangle and a star network inside it each of 2+(1/3) = 2.33 ohm.

-The 1 ohm each, resistors of outer triangular network and the above mentioned resistors of 2.33 ohm are in parallel connected with each other.

-Now, the circuit becomes a single wire triangular network with each side having a resistor of (1/R)=(1/1)+(1/2.33) 0.7 ohm.

-Select any two sides of this triangular network, it is clear that they are connected in series with each other and those serial resistors are in parallel connection with the resistor of the third side.

-Resistors in series of the final triangular network: 0.7+0.7=1.4 ohm

-The 1.4 ohm is in parallel connection with 0.7 ohm

-Equivalent resistance of the entire circuit between B and C is 0.42 ohm i.e 5/12 ohm (Option 'C')

-Convert the internal triangular network of resistors DEF from delta to star.

-As all the resistors of DEF are same i.e 1 ohm, the resistances of the star connection is (1x1)/(1+1+1)=1/3 ohm.

-Now these star resistors are connected in series with the 2 ohm resistors shown in the diagram with your question between AD, BE and FC.

-Therefore, the original network will now be reduced to the outward triangle and a star network inside it each of 2+(1/3) = 2.33 ohm.

-The 1 ohm each, resistors of outer triangular network and the above mentioned resistors of 2.33 ohm are in parallel connected with each other.

-Now, the circuit becomes a single wire triangular network with each side having a resistor of (1/R)=(1/1)+(1/2.33) 0.7 ohm.

-Select any two sides of this triangular network, it is clear that they are connected in series with each other and those serial resistors are in parallel connection with the resistor of the third side.

-Resistors in series of the final triangular network: 0.7+0.7=1.4 ohm

-The 1.4 ohm is in parallel connection with 0.7 ohm

-Equivalent resistance of the entire circuit between B and C is 0.42 ohm i.e 5/12 ohm (Option 'C')

### Answered by Abhijeet Mishra | 18th Jul, 2017, 02:09: PM

## Related Videos

- calculate the current of X resistor and power of X resistor
- Doubt
- 49
- A long uniform wire of resistance 9 ohm is bent into a circle. Two points of the wire at one third of the circumference apart are joined with a cell of emf 1.5 volt and internal resistance 0.5 ohm. Calculate the current in the different parts of the circuit.
- A resistance is made by joining two wires of same material. The radii of the two wires are 1mm and 3mm respectively,while their lengths are 3 cm and 5 cm respectively. A battery of emf 16 volt and negligible internal resistance is connected across the resistance. What is the potential drop along the shorter wire?
- Twelve resistances each of value 2 ohm are connected in the circuit. What is the effective resistance between A and C ?
- Two coils connected in series have a resistance of 18
_{}and when connected in parallel have a resistance of 4_{}. Find the value of individual resistances of the coils. - Find the current in the circuit shown in the figure below
- You are given n wires, each of resistance R. What is the ratio of maximum to minimum resistance obtained from these wires?
- A low voltage supply should have low resistance. Why?

### Kindly Sign up for a personalised experience

- Ask Study Doubts
- Sample Papers
- Past Year Papers
- Textbook Solutions

#### Sign Up

#### Verify mobile number

Enter the OTP sent to your number

Change