Circuits

Question 1

What is current?

Answer 1

considered the flow of positive charge

Question 2

What is the unit for conductivity?

Answer 2

Siemens (S) or Siemens/meter

Question 3

Metallic Conductivity relies on …..

Answer 3

the uniform movement of free electrons in metallic bonds

Question 4

Electrolytic Conductivity relies on ….

Answer 4

the ion concentration of a solution

Question 5

What is the equation for current?

Answer 5

I = Q/deltat 
Q = charge

Question 6

What is the unit for current?

Answer 6

ampere (1 A = 1 C/s)

Question 7

Direct Current vs Alternating Current

Answer 7

DC - charge flows in one direction only

AC - charge changes direction periodically

Question 8

What is electromotive force?

Answer 8

“pressure to move” - the voltage when there are no charges moving between the two terminals

Question 9

What is Kirchhoff’s two rules?

Answer 9

Junction Rule and Loop Rule

Question 10

What is Kirchhoff’s Junction Rule?

Answer 10

at any point or junction in a circuit, the sum of currents directed into that point equals the sum of current directed away from the point
Current(into junction) = Current(leaving junction)

Question 11

What is Kirchhoff’s Loop Rule?

Answer 11

Around any closed circuit loop, the sum of voltage sources will always be equal to the sum of voltage (potential) drops
V(source) = V(drop)

Question 12

What is voltage?

Answer 12

the potential difference between two points

Question 13

What is the unit for voltage?

Answer 13

volts (J/C)

Question 14

What is conductivity?

Answer 14

reciprocal of resistance; measure of permissiveness to current flow

Question 15

The conductivity in ______ solutions is always lower than in _____ solutions.

Answer 15

nonionic;ionic

Question 16

What is resistance?

Answer 16

the opposition within any material to the movement and flow of charge

Question 17

What is the equation for the resistance of a resistor?

Answer 17

R = pL/A 
R = resistance
p = resistivity
L = length of the resistor
A = cross-sectional area

Question 18

What is resistivity and its units?

Answer 18

p - intrinsic resistance to current flow in a material

units = ohm-meter

Question 19

If a resistor’s cross-sectional area is doubled, its resistance will be cut in ______.

Answer 19

half

Question 20

What are conduction pathways?

Answer 20

the number of pathways that current can flow through the resistor - the wider the resistor, the more pathways

Question 21

What is Ohm’s Law?

Answer 21

V = IR
V = voltage drop
I = current
R = magnitude of the resistance in ohms

Question 22

Equation for actual voltage of a cell

Answer 22

V = Ecell - ir(int)
r(int) - internal resistance of the cell
Ecell = emf of the cell
i = current through the cell

Question 23

What is the equation for power in relation to current?

Answer 23

P = IV
I = current
V = voltage

Question 24

Series vs Parallel

Answer 24

Series - which all current must pass sequentially through each resistor connected in linear arrangement
Parallel - which the current will divide to pass through resistors separately

Question 25

What is equivalent/resultant resistance?

Answer 25

the sum of all the individual resistances of resistors that are in series

Question 26

What is the equation for calculating resistance in parallel?

Answer 26

I/Rtotal = 1/R1 + 1/R2 + ... + 1/Rn

Question 27

The total resistance is _____ by wiring two identical resistors in parallel.

Answer 27

halved

Question 28

What are capacitors?

Answer 28

devices that can hold charge at a particular voltage

Question 29

What is the equation and units for capacitance?

Answer 29

``` C = Q/V Q = charge V = voltage Units = farad (1 F = 1 C/V) ```

Question 30

What is the equation for capacitance of a parallel plate?

Answer 30

``` C = E0*(A/d) E0 = 8.85 x 10 -12 F/m A = area of overlap of the two plates d = separation of the two plates ```

Question 31

What is the potential energy in a capacitor?

Answer 31

U = 1/2CV^2

Question 32

What is a dielectric material?

Answer 32

an insulator

Question 33

What is a dielectric constant?

Answer 33

(k) - measure of its insulating ability

Question 34

What is the equation with capacitance due to a dielectric material?

Answer 34

``` C' = kC C' = new capacitance with the dielectric present k = dielectric constant C = old capacitance ```

Question 35

What is the equation for the equivalent capacitance for capacitors in series?

Answer 35

1/Ctot = 1/C1 + 1/C2 + ... + 1/Cn

Question 36

What is the equation for the equivalent capacitance for capacitors in parallel?

Answer 36

Ctot = C1 + C2 + ... + Cn

Question 37

What are ammeters?

Answer 37

used to measure the current at some point within the circuit

Question 38

What is a voltmeter?

Answer 38

measure voltage drop across two points in a circuit

Question 39

What is an ohmmeter?

Answer 39

measure resistance