Star Delta Transformation MCQ [Free PDF] - Objective Question Answer for Star Delta Transformation Quiz

11. If a resistor R_x is connected between nodes X and Y, R_y between X and Y, R_z between Y and Z to form a delta connection, then after transformation to star, the resistor at node X is?

A. R_xR_y/(R_x + R_y + R_z)
B. R_xR_z/(R_x + R_y + R_z)
C. R_zR_y/(R_x + R_y + R_z)
D. (R_x + R_y)/(R_x + R_y + R_z)

Answer: A

After transformation to star, the resistor at node X is

R_xR_y/(R_x + R_y + R_z) and this resistance lies between R_x and R_y in the star connection.

12. If a resistor R_x is connected between nodes X and Y, R_y between X and Y, R_z between Y and Z to form a delta connection, then after transformation to star, the resistance at node Y is?

A. R_zR_y/(R_x + R_y + R_z)
B. R_zR_x/(R_x + R_y + R_z)
C. R_xR_y/(R_x + R_y + R_z)
D. (R_z + R_y)/(R_x + R_y + R_z)

Answer: B

After transformation to star, the resistor at node Y is

R_zR_x/(R_x + R_y + R_z) and this resistance lie between R_x and R_z in the star connection.

13. If a resistor R_x is connected between nodes X and Y, R_y between X and Y, R_z between Y and Z to form a delta connection, then after transformation to star, the resistance at node Z is?

A. R_yR_x/(R_x + R_y + R_z)
B. R_yR_x/(R_x + R_y + R_z)
C. R_zR_y/(R_x + R_y + R_z)
D. (R_z + R_x)/(R_x + R_y + R_z)

Answer: C

After transformation to star, the resistor at node Y is

R_zR_y/(R_x + R_y + R_z) and this resistance lie between R_z and R_y in the star connection.

14. If the resistors of a star-connected system are R₁, R₂, and R₃ then the resistance between 1 and 2 in delta connected system will be?

A. (R₁R₂ + R₂R₃ + R₃R₁)/R₃
B. (R₁R₂ + R₂R₃ + R₃R₁)/R₁
C. (R₁R₂ + R₂R₃ + R₃R₁)/R₂
D. (R₁R₂ + R₂R₃ + R₃R₁)/(R₁ + R₂)

Answer: A

After transformation to delta, the resistance between 1 and 2 in delta connected system will be

(R₁R₂ + R₂R₃ + R₃R₁)/R₃

This resistance lies between R₁ and R₂ in the delta connection.

15. If the resistors of a star-connected system are R₁, R₂, and R₃ then the resistance between 2 and 3 in delta connected system will be?

A. (R₁R₂ + R₂R₃ + R₃R₁)/R₃
B. (R₁R₂ + R₂R₃ + R₃R₁)/R₂
C. (R₁R₂ + R₂R₃ + R₃R₁)/R₁
D. (R₁R₂ + R₂R₃ + R₃R₁)/(R₃ + R₂)

Answer: C

After transformation to delta, the resistance between 2 and 3 in delta connected system will be (R₁R₂ + R₂R₃ + R₃R₁)/R₁ and this resistance lies between R₃, and R₂ in delta connection.

16. If the resistors of a star-connected system are R₁, R₂, and R₃ then the resistance between 3 and 1 in delta connected system will be?

A. (R₁R₂ + R₂R₃ + R₃R₁)/R₁
B. (R₁R₂ + R₂R₃ + R₃R₁)/R₃
C. (R₁R₂ + R₂R₃ + R₃R₁)/R₂
D. (R₁R₂ + R₂R₃ + R₃R₁)/(R₃ + R₁)

Answer: C

After transformation to delta, the resistance between 2 and 3 in delta connected system will be

(R₁R₂ + R₂R₃ + R₃R₁)/R₂

This resistance lies between R₁ and R₃ in the delta connection.

17. Find the equivalent resistance at node A in the delta connected circuit as shown in the figure below.

A. 1
B. 2
C. 3
D. 4

Answer: D

Performing delta to star transformation we obtain the equivalent resistance at node A is R = (11×12)/(11 + 12 + 13) = 4Ω.

18. Find the equivalent resistance at node C in the delta connected circuit as shown below.

A. 3.66
B. 4.66
C. 5.66
D. 6.66

Answer: B

Performing delta to star transformation we obtain the equivalent resistance at node A is

R = (12×13)/(11 + 12 + 13) = 4.66Ω.

19. Find the equivalent resistance between node 1 and node 3 in the star-connected circuit shown below.

A. 30
B. 31
C. 32
D. 33

Answer: C

The equivalent resistance between node 1 and node 3 in the star connected circuit is

R = (10×10 + 10×11 + 11×10)/10 = 32Ω.

20. Find the equivalent resistance between node 1 and node 2 in the star-connected circuit as shown below.

Find the equivalent resistance between node 1 and node 3 in the star-connected circuit is shown below.

A. 2
B. 29
C. 30
D. 31

Answer: B

The equivalent resistance between node 1 and node 3 in the star connected circuit is

R = (10×10 + 10×11 + 11×10)/11 = 29Ω.

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