Electrical Principles Week 7

Question 1

Define electric current and its unit.

Answer 1

Rate of flow of charge (I; Amps)

Question 2

What is the formula that relates electric current (I), charge (Q), and time (t)?

Answer 2

I = dQ/dt

Question 3

What does voltage (V) represent and what is its unit?

Answer 3

Electrical potential difference; volts

Question 4

What is resistance (R) and how is it defined?

Answer 4

Opposition to the flow of charge through a conductor
R = V/I

Question 5

What is Ohm’s Law?

Answer 5

V = IR
V- potential difference
I - current
R - resistance

Question 6

What is conductance (G) and its unit?

Answer 6

Reciprocal of resistance; siemens (S)

Question 7

What is the relationship for resistors connected in series?

Answer 7

R_total = R1 + R2 + …

Question 8

What is the relationship for resistors connected in parallel?

Answer 8

1/R_total = 1/R1 + 1/R2 + …

Question 9

What is a capacitor and its unit?

Answer 9

Device that stores charge; farads (F)

Question 10

What is the electrostatic force between charges?

Answer 10

F is inversely proportional to the distance (r) between them: F ∝ 1/r²

Question 11

What is the unit of charge?

Answer 11

Coulomb (C)
Q in equations

Question 12

What is the elementary charge of an electron?

Answer 12

1.602 x 10^-19 C
Charge carried by a single proton (e) or a charge carried by a negative electron (-e)

Question 13

What is the Faraday constant (F)?

Answer 13

Charge on 1 mole of electrons; 9.648 x 10^4 C/mol

Question 14

What is the Avogadro constant?

Answer 14

6.022 x 10^23 mol^-1
Number of electrons in 1 mole of electrons

Question 15

What does an electric field represent?

Answer 15

Region where an electric force is experienced

Question 16

What is the formula for force (F) on a charged body in an electric field?

Answer 16

F = EQ’
F - force ( in Newtons )
Q - charge experienced around the body
E - strength of the field

Question 17

What is the unit of electric potential?

Answer 17

Volt (V)

Question 18

Define potential difference.

Answer 18

Energy expended on moving a charge from one point to another

Question 19

What is the relationship between work (W), charge (Q), and potential difference (V)?

Answer 19

W = QV

Question 20

What is the definition of one volt?

Answer 20

1 V = 1 J/C

Question 21

What is the biological significance of membrane potential (Vm)?

Answer 21

Difference in potential measured across a cell membrane

Question 22

What type of ions move towards a cathode?

Answer 22

Positively charged ions

Question 23

What type of ions move towards an anode?

Answer 23

Negatively charged ions

Question 24

What distinguishes electrolytes from non-electrolytes?

Answer 24

Electrolytes conduct electricity in solution, non-electrolytes do not

Question 25

What is the unit symbol for current?

Answer 25

A (ampere)

Question 26

What is the unit symbol for resistance?

Answer 26

Ω (ohm)

Question 27

What is the unit symbol for capacitance?

Answer 27

F (farad)

Question 28

Fill in the blank: The potential difference between two points A and B is one volt if the work done in taking one coulomb of positive charge from B to A is _______.

Answer 28

one Joule

Question 29

What are conductors?

Answer 29

Solid materials that let electrons move freely through solid

Question 30

What are insulators?

Answer 30

Materials that hold onto electrons tightly, limiting their movement.

Question 31

What is electrostatic force?

Answer 31

Attraction / repulsion between ions/charges.

Question 32

How is an electric field mapped?

Answer 32

By electrostatic line of force also known as electric flux.