Chapter 2. Basic Laws of DC Circuits

Question 1

What is Ohm’s Law?

Answer 1

v = iR

i = v/R

R = v/i

Question 2

If current flows from high potential to low potential, voltage is…

Answer 2

voltage is positive

Question 3

If current flows from low potential to high potential, voltage is…

Answer 3

voltage is negative

Question 4

What’s a short circuit?

Answer 4

connection with near zero resistance.

v = i * 0 -> v = 0

can be represented by a connecting wire

Question 5

What’s an open circuit

Answer 5

connection with infinite resistance

i = v/ ∞ = 0

represented by an incomplete/broken path

Question 6

What’s a branch?

Answer 6

represents a single element

Question 7

What’s a node?

Answer 7

is point of connection between two or more branches

Question 8

What’s a loop?

Answer 8

is any closed path in a circuit

Question 9

When is a loop independent?

Answer 9

A loop is independent if it contains at least one branch not shared by any other independent loops

Question 10

When are two elements in series?

Answer 10

if two elements share ONE common node, and no other element is connected

Question 11

what is true about the current in elements in series?

Answer 11

Both elements carry the same current

Question 12

When are two elements in parallel?

Answer 12

if they are connected to the same TWO nodes, and thus have the same voltage

Question 13

Two or more series connected voltage sources can be replaced by…

Answer 13

one source which represents the equivalent voltage from all sources

Question 14

Can voltage sources be connected in parallel?

Answer 14

NO, the potential difference between both nodes must be the same

Question 15

Can current sources be connected in series?

Answer 15

NO, because the current has to be the same through one wire

Question 16

Two or more parallel connected current sources can be replaced by…

Answer 16

one source which represents the equivalent current from the two sources

Question 17

What is KCL?
What sign is current entering a node and what sign is current leaving?

Answer 17

states that the current entering a node must equal the current leaving a node.

current entering = negative
current leaving = positive

Question 18

What is KVL?

How do we determine sign?

Answer 18

The sum of all voltages in a closed loop is zero

the sign on each voltage depends on which terminal is encountered first

Question 19

What is the equivalent resistance for resistors in series?

Answer 19

equals to the sum of all individual resistance values connected in series

Req = ΣRn

Question 20

What is voltage division?

Answer 20

allows us to calculate the voltage drop across any one resistor in a series circuit

Question 21

How do we find the voltage across any one resistor in a series circuit?
(voltage division)

Answer 21

Vn = (Rn/ ΣR)*Vsource

the resistance we’re looking at divided by the sum of all resistors, multiplied by the voltage from the source

Question 22

What is the equivalent resistance for resistors in parallel?

Answer 22

the voltage drop across parallel resistors are the same.

1/ Req = (1/R1) + (1/R2) + … + (1/Rn)

Question 23

What should be true about equivalent resistance and the smallest resistor (in parallel resistors)

Answer 23

Req should always be less than the smallest resistor

Question 24

How do we calculate the current across any resistors in a parallel circuit? (all resistors are parallel with each other

Answer 24

in = (Req/Rn)*i

i is the current source