Network Analysis

Question 1

Methods of solving electrical networks

Answer 1

Superposition theorem
Kirchoffs Laws
Thevenin and Norton Equivalent Circuits

Question 2

What is a passive networks

Answer 2

it contains no source of emf

Question 3

What is an active network

Answer 3

it does contain an emf

Question 4

What is superposition theorem

Answer 4

It is the process of considering each emf source in turn, with all other sources being represented by their internal resistance
resultant currents is obtained from algebraic sum of the currents from each source

Question 5

In superposition theorem what should you do to voltage and current sources

Answer 5

short circuit voltage sources and open circuit current sources

Question 6

If current is flowing into a battery what is happening

Answer 6

the battery is being charged

Question 7

What is a node

Answer 7

the point where two or more branches meet

Question 8

What is a branch

Answer 8

Part of a circuit connecting two nodes

Question 9

What is a loop

Answer 9

closed path formed by connecting branches

Question 10

What is kirchoffs first law

Answer 10

The algebraic sum of all the instantaneous currents entering any node is zero at all times

Question 11

Kirchoffs second law

Answer 11

instantaneous voltages around a loop is zero at all times

Question 12

When is thevenin theorem useful

Answer 12

when load resistance is changing saves having to reanalyse the whole circuit

Question 13

How does Thevenin work

Answer 13

an active network having two terminals (A and B) can be replaced by a constant voltage source E, the magnitude of which is equal to the open circuit voltage between A and B and an internal resistance r, r is the resistance between A and B with the load disconnected and emf sources replaced by their internal resistance

Question 14

Steps for Thevenin

Answer 14

short circuit voltage sources and open circuit current sources
ignore the load voltage for the mean time
calculate the total resistance = r
Calculate voltage across the terminals = E

Question 15

What is a replacement thevenin circuit made up of

Answer 15

A voltage supply E with internal resistance r connected to two terminals, across which a load may be connected

Question 16

What is a norton equivalent circuit

Answer 16

An active network having 2 terminal A and B can be replaced by a constant current source Is where Is is equal to the short circuit current at the terminals and a shunt resistance r which is equal to the resistance between A and B with the sources removed

Question 17

Relationship between Norton and Thevenin resistance

Answer 17

they are both the same

Question 18

Parts of a norton equivalent circuit

Answer 18

constant current source with a resistor of resistance r across it

Question 19

Key step for norton

Answer 19

short circuit the terminals and find the current flowing through them

Question 20

How to find the norton circuit from thevenin

Answer 20

the thevenin equivalent should be equal to the norton equivalent, so short circuit the thevenin circuit to find the current

Question 21

When comparing circuits from one setup to the next generally what will it ask you to compare

Answer 21

the current coming from the source, across the entire circuits resistance

Question 22

If a current source has infinite internal resistance what is the current across the load

Answer 22

as the internal resistance is infinite the load current will be equal to the current supplied by the current source

Question 23

If multiple sources in thevenin and norton how should you proceed

Answer 23

Use superposition to find voltages across A and B

Question 24

While working out thevenin emf what may the terminals be considered as

Answer 24

a voltmeter