Physics #6

Question 1

current is considered the flow of _____ charge even though _____ are actually moving

Answer 1

positive charge

negative

Question 2

compare metallic and electrolytic conductivity

Answer 2

metallic: solid metals and molten forms of salts
electrolytic: in solutions

Question 3

conductance

Answer 3

reciprocal of resistance

Question 4

metallic conductivity

Answer 4

sea of electrons flowing all throughout the metallic mass.

Question 5

electrolytic conductivity

Answer 5

depends on the strength of a solution (concentration)

Question 6

what is the formal definition of current

Answer 6

the amount of charge passing through a conductor per unit time.

Question 7

the direction of current is ______ the direction of electron flow

Answer 7

opposite

Question 8

compare direct current (DC) and alternating current (AC)

Answer 8

direct current: charge flows in one direction only

alternating current: the flow of charge changes periodically.

Question 9

Kirchhoff’s Junction Rule

Answer 9

at any point or junction, the sum of currents directed into that point equals the sum of currents directed away from that point

Question 10

electromotive force vs. voltage

Answer 10

voltage: the potential difference between two points
emf: the potential difference of the voltage source for a circuit

Question 11

does electrical current follow the continuity equation that fluids follow?

Answer 11

no

Question 12

most conductors have ____ resistance at higher temperatures

Answer 12

greater

Question 13

superconductors

Answer 13

when they are cooled to very low temperatures, the resistivity of the material drops to 0.

Question 14

the rate at which energy is dissipated by a resistor is the ____ of the resistor

Answer 14

power

Question 15

why is resistance decreased when resistors are added in parallel

Answer 15

more pathways, greater surface area.

Question 16

when n identical resistors are wired in parallel, the total resistance is given by ____

Answer 16

R/n

Question 17

In parallel, when a resistor is added, the overall resistance _____

Answer 17

decreases

Question 18

The internal resistance of a battery will ____ the amount of current it can provide.

Answer 18

decrease

Question 19

capacitance

Answer 19

the ratio of the magnitude of the charge stored on one plate to the potential difference (voltage) across the capacitor

Question 20

how much is a picofarad?

Answer 20

10^-12 farads

Question 21

the dielectric constant of a material is a measure of its ____

Answer 21

insulating ability

Question 22

can a dielectric material decrease the capacitance?

Answer 22

no

Question 23

what happens when a dielectric material is placed in an isolated, charged capacitor that is disconnected from any circuit?

Answer 23

decrease in voltage but increase in capacitance

charge stays the same

Question 24

what happens when a dielectric material is placed in a charged capacitor within a circuit that is still connected to a voltage source?

Answer 24

the charge on the capacitor increases and the capacitance increases.
voltage stays the same

Question 25

ammeter

Answer 25

used to measure the current at some point within a circuit
placed in series, no voltage drop and no resistance
requires a circuit to be active

Question 26

voltmeter

Answer 26

requires a circuit to be active
measures a voltage drop
wired in parallel
infinite resistance (current will never go its way)

Question 27

ohmmeter

Answer 27

does not require a circuit to be active
measures resistance
often have their own battery of known voltage