Circuits

Question 1

Current

Answer 1

Flow of positive charge–even though only negative charges are moving

Question 2

Metallic conductivity

Answer 2

Solid metals & molten forms of some salts

Question 3

Electrolytic conductivity

Answer 3

conductivity in solutions

Depends on the concentration of the solution

Question 4

Conductance

Answer 4

Reciprocal of resistance 
in siemens (S) or siemens/meter (S/m)

Question 5

Magnitude of current

Answer 5

I=Q/Delta(t)

Question 6

Which way is current

Answer 6

Direction of the positive charge would flow

Question 7

DC (direct current)

Answer 7

Charge flows in one direction only

Question 8

AC (Alternating current)

Answer 8

Current flow changes direction periodically

Question 9

Electromotive force (emf or e)

Answer 9

when no charge is moving between two terminals of a cell, they are at different potential values (in volts or J/C

Question 10

Kirchhoff’s Laws

Answer 10

Conservation of charge & energy in a circuit

Question 11

Kirchhoff’s Junction Rule

Answer 11

At any point or junction in a circuit, the sum of the currents directed into that point equals the sum of currents directed away from that point

Question 12

Kirchhoff’s Loop Rule

Answer 12

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

Question 13

Resistance

Answer 13

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

Question 14

Resistance equation

Answer 14

R=pL/A

in Ohms

Question 15

Resistivity

Answer 15

Intrinsic resistance to current flow in material

in Ohm meters

Question 16

What happens to resistance as temperature increases?

Answer 16

It increases

Question 17

Ohm’s Law

Answer 17

V=IR

Question 18

Actual voltage supplied by a cell

Answer 18

V=E(cell) - ir(int

E(cell)= emf of the cell
i=current through cell
rint=internal resistance

Question 19

What is the internal resistance when there is no current?

Answer 19

0

Question 20

What is the voltage of a cell when it is open?

Answer 20

=emf

Question 21

How does the voltage of a cell compare when the current is flowing to when its not?

Answer 21

Less voltage when it is flowing

Question 22

What kind of cell recharges

Answer 22

Electrolytic

From low to higher potential

Question 23

What kind of cell discharges

Answer 23

Galvanic (voltaic)

Question 24

Power of a resistor

Answer 24

Rate at which energy is dissipated by a resistor

Question 25

Power of a resistor equation

Answer 25

P= IV=I^2R=V^2/R

Question 26

How are resistances & voltages in series treated?

Answer 26

Additive voltage drops & resistance

Question 27

How are resistance & voltages in parallel treated?

Answer 27

All voltages are equal | Resistance is reciprocal added

Question 28

What is the effect of adding resistors in parallel?

Answer 28

Reducing resistance

Question 29

Capacitator

Answer 29

Hold charge at a particular voltage

Question 30

Capacitance

Answer 30

Charge (Q)/Potential difference (V)

Question 31

Parallel plate capacitance

Answer 31

C=eo(A/d)

Question 32

Uniform electric field equation

Answer 32

E=V/d

Question 33

What is the direction on capacitor plate?

Answer 33

From positive to negative plate

Question 34

Potential energy stored in a capacitor

Answer 34

U=1/2CV^2

Question 35

Dielectric material

Answer 35

Insulation, introduced between capacitator plates & will increase the capacitance by a factor call the dielectric constant (k)

Question 36

Capacitance due to a dielectric material

Answer 36

C'=kC

Question 37

Can a dielectric material decrease the capacitance?

Answer 37

No, k is never less than 1

Question 38

Where does increase in capacitance come from in isolated (no circuit capacitators?

Answer 38

Decrease in voltage

Question 39

Where does increased capacitance come from in a capacitator in a circuit?

Answer 39

Increase in stored charge on the capacitator

Question 40

What stays constant in an isolated capacitator?

Answer 40

Charge

Question 41

What stays constant in a capacitaotr in a circuit?

Answer 41

Voltage

Question 42

What happens to capacitators in series?

Answer 42

Decrease capacitance Reciprocal effect Total voltage=sum of all voltages

Question 43

What happens to capacitators in parallel?

Answer 43

Addition of all capacitances | Voltages all equal to the source voltage

Question 44

Anmeter

Answer 44

Used to measure current (low resistance & voltage drop) | Placed in series with the point

Question 45

Voltmeter

Answer 45

Measure voltage drop across two points, wired in parallel to two points (infinite resistance)

Question 46

Ohmmeter

Answer 46

Doesn't require a circuit to be active Have their own battery of a voltage & finding current to find resistance Wired in series of two points

Question 47

How is current calculated with resistors in series?

Answer 47

All currents are equal

Question 48

How is current calculated with resistors in parallel?

Answer 48

All currents are added

Question 49

What is the potential difference around a loop?

Answer 49

0 V | Kirchoff's Loop Rule states that voltage gained by the battery will be used up by the resistors

Question 50

How to find electromotive force?

Answer 50

Voltage across terminals of battery when no current is flowing Use V=e-ir(int)