Electricity basics

Question 1

what is current?

Answer 1

flow of charge

Question 2

what is the symbol for current?

Answer 2

I or i for an instantaneous value that changes with time

Question 3

what is 1A equal to?

Answer 3

1C/s

Question 4

what is electrical potential?

Answer 4

describes forces which act on charges in terms of work done moving them from one point to another

Question 5

what is the symbol for voltage?

Answer 5

V or v for an instantaneous value

Question 6

what is 1V of electrical pot diff?

Answer 6

1J of work is done to move 1C positive charge from A to B

Question 7

what is pd produced by in circuits?

Answer 7

emf

Question 8

what is emf?

Answer 8

driving force which can maintain current around a closed path

Question 9

what is Ohm’s law?

Answer 9

V=IR

Question 10

when is a current produced?

Answer 10

when there is a difference in V between two points/across a component

Question 11

what is the symbol for conductance?

Answer 11

G

Question 12

what is the units for conductance?

Answer 12

siemens (s)

Question 13

what is conductance?

Answer 13

inverse of resistance

Question 14

what is a superconductor?

Answer 14

has 0 resistance

Question 15

what is capacitance?

Answer 15

charge per unit pd

Question 16

what is the symbol for capacitance?

Answer 16

C

Question 17

what are the units for capacitance?

Answer 17

Farad

Question 18

what does pd generally have a relation with and how?

Answer 18

proportional to charge

Question 19

what does C depend on?

Answer 19

geometry and material

Question 20

what are the equations for i?

Answer 20

i = dq/dt = C dv/dt

Question 21

what is C usually like?

Answer 21

constant

Question 22

when does current flow between two conducting plates when a pd is applied?

Answer 22

only if q changes with time

Question 23

what is the equation for V in terms of time?

Answer 23

v(τ) = (1/c * ∫i(t) dt between τ and 0) + v(0)

Question 24

what does electric current produce?

Answer 24

a magnetic field

Question 25

when is a magnetic flux produced?

Answer 25

when current flows around a closed system

Question 26

what is the symbol for magnetic flux?

Answer 26

ɸ

Question 27

what is the symbol for inductance?

Answer 27

L

Question 28

what is the equation for inductance?

Answer 28

L = ɸ/i

Question 29

what does ɸ have a relation with and how?

Answer 29

proportional to i

Question 30

what are the units of L?

Answer 30

Henry (H)

Question 31

when is an emf induced and why?

Answer 31

if current changes as flux changes

Question 32

what are the equations for emf?

Answer 32

emf = dɸ/dt = L di/dt

Question 33

what is the equation for i as a function of time?

Answer 33

i(τ) = (1/L * ∫v(t) dt between τ and 0) + v(0)

Question 34

draw the symbol for a capacitor

Answer 34

check electricity handout, page 6

Question 35

draw the symbol for an inductor

Answer 35

check electricity handout, page 6

Question 36

what is the equation for resistivity?

Answer 36

R = 𝜌 * L lowercase / A

Question 37

what is impedance?

Answer 37

measure of opposition of a component to current

Question 38

what is the symbol for impedance?

Answer 38

Z

Question 39

what is the equation for Z?

Answer 39

Z = R + jX

Question 40

what is the symbol for reactance?

Answer 40

X

Question 41

what is j?

Answer 41

√-1

Question 42

what are the assumptions of an open DC circuit?

Answer 42

all capacitors have ∞ R

Question 43

what are the assumptions of a closed DC circuit?

Answer 43

all inductors have 0 resistance

Question 44

what is the equation for power dissipated?

Answer 44

P = IV

Question 45

what is a node?

Answer 45

where circuits join

Question 46

which direction does current flow?

Answer 46

high to low voltage