Unit 1

Unit 1

DC Circuits

Question 1. Find the current through resistance.

Solution:

1= 0

2=

1 + 2 

Special Case:

Since two voltage sources with different magnitude in parallel which cannot be connected as in single branch two different current is not possible (if 5V than I = zero).

Question 2:

1 =

2 =

=

1 + 2

=

Question 3:

Answer:

Finding Isc from circuit directly:

By KCL,

Question 4:

Answer

Also, clear from circuit that Vth = 1V.

By applying KVL we get,

1-3Isc=0

Isc=A

Que 5:

Ans;

Rth=3k+2k=5k

By applying KVL we get

Therefore,

Question 6:

Solution: For Rth

By KCL,

     But,

By KVL,

Question 7:

Solution: Since, no independent source is present so,

Isc = 0

And we know that,

Since Rth cannot be zero

       But

Q 8 Explain Star Delta transformation

Star to delta conversion to final equivalent resistance

We know that (from delta to star conversion)

R1 =    …….①

R2 = …..②

R1 = ……③

Multiply ① X ② L.H.S and R.H.S

R1 R2 = …….④   where  

Similarly multiply  ② X ③

R2 R3 = …….⑤

And ③  X①

R1 R3 = …….⑥

Now add equation ④, ⑤, and ⑥ L.H.S and R.H.S

……refer eq. ②

= + +

=  +

(Delta)      star             star

Similarly R23 = R2+R3 +

R23 = R1+R2 +