Electric Fields, Current, Potential Difference

Question 1

Electric field point away or to positive source charges?

Answer 1

Electric fields point away from positive source charges

Question 2

How many charges are needed to create an electric field?

Answer 2

one

Question 3

How many charges are needed to create an electric force?

Answer 3

two charges

Question 4

If there is a uniform magnetic field, what is electrostatic force?

Answer 4

Electrostatic force and particle acceleration will be constant

Question 5

When will a field do work?

Answer 5

Only if there is displacement in direction of electric field or opposite of electric field

Question 6

What is an electric dipole?

Answer 6

Equal but opposite charges

Question 7

If a conductor is placed in an electric field, what happens?

Answer 7

conduction electrons will move in response to the field

Question 8

Why is there no electrostatic field inside a conductor?

Answer 8

There is no excess charge within a conductor

Question 9

If an external electric field is brought to a conductor what happens?

Answer 9

free charges move to the surface and shield the interior to keep the electric field zero inside

Question 10

What are equipotentials?

Answer 10

Potentials that are the same within the electric field

Question 11

Electric potential is inversely proportional to what?

Answer 11

the distance

Question 12

When is there no change in potential energy for a charge?

Answer 12

When initial and final positions are at the same potential

Question 13

When moving with nature, the change in potential energy is positive or negative?

Answer 13

negative. Potential decreases

Question 14

When moving against nature, the change in potential energy is positive or negative?

Answer 14

Positive. Potential increases

Question 15

When is mechanical energy conserved?

Answer 15

if there is no friction or other forces doing work while the charge moves.

Question 16

What is electric circuit?

Answer 16

pathway for movement of electric charge, consisting of voltage source, connecting wires, and other compounds

Question 17

What is current?

Answer 17

Movement of charge

Question 18

What is drift velocity?

Answer 18

slight movement of conduction electrons in a particular direction

Question 19

What is the unit for current?

Answer 19

Amps

Question 20

What is the unit for voltage/ potential difference?

Answer 20

Voltage

Question 21

If there is voltage, what else is likely present?

Answer 21

current

Question 22

What is another name for electormotive force?

Answer 22

voltage

Question 23

What kind of intrinsic resistance do metals have?

Answer 23

low intrinsic resistance

Question 24

What is the unit of resistance?

Answer 24

Ohm or Volts per Amp

Question 25

Resistance is directly proportional to what?

Answer 25

Length of wire

Question 26

Resistance is inversely proportional to what?

Answer 26

square of diameter or area of wire

Question 27

What is resistivity?

Answer 27

expresses resistance in terms of materials intrinsic resistance

Question 28

Resisitivity of conductors increases with what?

Answer 28

temperature

Question 29

When is Ohm's Law obeyed?

Answer 29

When resistance is constant and voltage is varied. If voltage is reversed, polarity must be reversed

Question 30

What is Ohm's Law?

Answer 30

Voltage equals Current times Resistance

Question 31

What is a DC circuit?

Answer 31

Simple circuit that has a voltage source connecting wires to a positive terminal and negative terminal

Question 32

What terminal has higher potential in a DC circuit?

Answer 32

Positive terminal

Question 33

What terminal has lower potential in a DC Circuit?

Answer 33

Negative terminal

Question 34

Which direction does conduction electrons drift in a DC circuit?

Answer 34

low to high potential or negative to postive

Question 35

What is the direction of current in a DC circuit?

Answer 35

counterclockwise going negative to positive

Question 36

In series resistors, what are the quantities of current and voltage?

Answer 36

Current is the same and voltage is different

Question 37

In parallel resistors, what are the quantitites of current and voltage?

Answer 37

Voltages are the same and currents are different

Question 38

What is Kirchhoff's law dealing with voltage?

Answer 38

for a circuit with one battery used as voltage source, sum of voltage drops across resistors starting at positive terminal and ending at negative terminal.

Question 39

What is kirchhoff's law dealing with current?

Answer 39

Amount of current entering parallel combination is equal to sum of currents that pass through all individual resistors in combination

Question 40

What does power for resistors equal?

Answer 40

Power equals Current squared times resistance

Question 41

What is power dissipated by resistors equal to?

Answer 41

Power supplied by battery. conservation of energy

Question 42

What does power equal for a circuit?

Answer 42

Power equals Current times voltage

Question 43

What are voltmeters used for?

Answer 43

to measure the voltage between two points in a circuit

Question 44

What are ammeters used for?

Answer 44

Measure current through a particular point in circuit

Question 45

What is a galvonometer?

Answer 45

measures current using interaction between currents and magnetic fields

Question 46

What is a capacitor?

Answer 46

pair of conductors that hold equal but opposite charges

Question 47

What is the net charge of a capacitor?

Answer 47

zero

Question 48

What are the units for capacitance?

Answer 48

Faraday or Coulomb per volt

Question 49

What is capacitance determined by?

Answer 49

sizes of plates and how far apart they are

Question 50

To keep voltage low would we want a capacitor of greater or lesser capacitance?

Answer 50

greater

Question 51

What are the two uses for a parallel plate capacitor?

Answer 51

create a uniform electric field and store electric potential energy

Question 52

Electric Fields between capacitors always point in which direction?

Answer 52

positive to negative

Question 53

How is potential energy stored between plates?

Answer 53

voltage source must do work against electric field created between plates of capacitor

Question 54

What does an insulator do for capacitance?

Answer 54

It increases