Chapters 13 and 14: Electricity

Question 1

What is current?

Answer 1

The rate of flow of charge

Question 2

What is the equation for current?

Answer 2

I = ∆Q / ∆t

Question 3

What is potential difference?

Answer 3

The amount of electrical work done per unit charge through a component

Question 4

What is the equation for potential difference?

Answer 4

V = W/ Q

Question 5

What is electromotive force?

Answer 5

The amount of electrical work done per unit charge by a power supply in an electric circuit

Question 6

What is the equation for electromotive force?

Answer 6

ε = E/Q

Question 7

What is resistance?

Answer 7

A measure of the opposition of a conductor to electric current flowing through it

Question 8

What is the equation for Ohm’s Law?

Answer 8

R = V/ I

Question 9

What is Ohm’s Law?

Answer 9

The current and potential difference through an ohmic conductor under constant physical conditions are proportional

Question 10

What is a thermistor?

Answer 10

A temperature sensitive semiconductor whose resistance increases when temperature decreases. It has a negative temperature coefficient

Question 11

What is a superconductor?

Answer 11

A material which has zero resistivity when the temperature is decreased to, or below, the material’s critical temperature.

Question 12

What are some real applications of superconductors?

Answer 12

Maglev trains, MRI scanners, particle accelerators

Question 13

What can superconductors be generally used for?

Answer 13

The production of strong magnetic fields and the reduction of energy loss in transmission of electric power

Question 14

What is resistivity?

Answer 14

The intrinsic resistance of a material independent of the dimensions of the substance

Question 15

What is the equation for resistivity?

Answer 15

ρ= RA/l

Question 16

What are three equations for power through a component?

Answer 16

P = IV
P = I2R
P= V2 / R

Question 17

What is Kirchoff’s first circuit law?

Answer 17

Sum of I = 0

Question 18

What is Kirchoff’s second circuit law?

Answer 18

Sum of emf = sum of pd

Question 19

What is a potential divider?

Answer 19

A method of splitting a potential difference, by connecting two resistors in series. The total potential difference is split in the ratio of their resistances.

Question 20

What is internal resistance?

Answer 20

The resistance to the flow of charge within a source. Internal resistance results in energy being dissipated within the source.

Question 21

What is the equation for internal resistance?

Answer 21

V = ε - rI

Question 22

What is the terminal pd?

Answer 22

The potential difference across the terminals of a power source. It is equal to the source’s emf minus any voltage drop over them source’s internal resistance.