Electrical Circuits & Network Theorems: Direct Current Circuits Diagrams, Resistance And Its Types

Direct Current Circuits Diagrams, Resistance And Its Types

All components which are used to design in a dc network circuit are shown in the block diagram. Circuit consists of two main things;

1) Source

2) Load or Element

All the further classification of source and load are shown in block diagram.

NOTE: - For the analysis of direct current network, we divide it into two parts.

In 1st part we are only studied about independent source and resistance.

2nd part will contents dependent source as well as independent source and both type of element (i.e., restive & reactive element).

1) Independent source :-

A. Voltage source/Battery source/Emf source:-

Symbol:-

Direction of current through a voltage source:-

In the above fig. –ve sign indicates lower potential and the +ve sign indicates higher potential of an emf source.So, the direction of flow of current in a battery source is from lower potential to higher potential(i.e,from –ve sign to +ve sign).

B. Current Source:-

Symbol:-

Direction of current through a current source:-

In the above fig. arrow indicates the flow of current.

Note:-Current always measure in ampere (A). Voltage always measure in volt (v).

3) Resistance:-

Symbol:-

“It is the property of a material which opposes the flow of current.”

It is indicated by “R”. And its S.I unit is “ohm” or “Ω”.

Grouping of resistance:-

There are three types of grouping of resistance.

They are:-

a) Series connection/combination

b) Parallel connection/combination

c) Mixed connection/combination

A) Series connection/combination:-

No. of resistance are adding in such a way it’s tail connected to the head of new resistance

and so on, the arrangement is called “series connection”.

i.e,

Formula for series connection,

Rseries or Req=R1+R2+R3+R4+-------------+Rn

Note:- In series connection, current will be same but voltage will be different.

(Req or equivalent resistance is also the representation of more than one resistance into single resistance.)

B) Parallel Connection/Combination:-

No. of resistance adding in such a way its head is fixed to a point and its tail is fixed to the another point, this arrangement is called “Parallel combination”.

i.e.,

Formula for Parallel connection,

1/Req or Rparallel=1/R1+1/R2+1/R3+----------+1/RN

Note:-In Parallel connection, voltage will be same but current will be different.

FORMULA FOR TWO PARALLEL RESISTANCE:-

This is the shortcut formula for two parallel resistances.

FORMULA FOR TWO IDENTICAL PARALLEL RESISTANCE:-

Here, R1=R2=R(say)

So, when two identical resistances are in parallel combination then its equivalent becomes half of that identical resistance.

Mixed Connection/Combination:-

The arrangement in both types of connection are used is known as “Mixed combination”.

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