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MCAT > Electric Fields, Current, Potential Difference > Flashcards

Electric Fields, Current, Potential Difference Flashcards

1
Q

Electric field point away or to positive source charges?

A

Electric fields point away from positive source charges

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2
Q

How many charges are needed to create an electric field?

A

one

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3
Q

How many charges are needed to create an electric force?

A

two charges

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4
Q

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

A

Electrostatic force and particle acceleration will be constant

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5
Q

When will a field do work?

A

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

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6
Q

What is an electric dipole?

A

Equal but opposite charges

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7
Q

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

A

conduction electrons will move in response to the field

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8
Q

Why is there no electrostatic field inside a conductor?

A

There is no excess charge within a conductor

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9
Q

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

A

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

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10
Q

What are equipotentials?

A

Potentials that are the same within the electric field

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11
Q

Electric potential is inversely proportional to what?

A

the distance

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12
Q

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

A

When initial and final positions are at the same potential

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13
Q

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

A

negative. Potential decreases

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14
Q

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

A

Positive. Potential increases

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15
Q

When is mechanical energy conserved?

A

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

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16
Q

What is electric circuit?

A

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

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17
Q

What is current?

A

Movement of charge

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18
Q

What is drift velocity?

A

slight movement of conduction electrons in a particular direction

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19
Q

What is the unit for current?

A

Amps

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20
Q

What is the unit for voltage/ potential difference?

A

Voltage

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21
Q

If there is voltage, what else is likely present?

A

current

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22
Q

What is another name for electormotive force?

A

voltage

23
Q

What kind of intrinsic resistance do metals have?

A

low intrinsic resistance

24
Q

What is the unit of resistance?

A

Ohm or Volts per Amp

25
Q

Resistance is directly proportional to what?

A

Length of wire

26
Q

Resistance is inversely proportional to what?

A

square of diameter or area of wire

27
Q

What is resistivity?

A

expresses resistance in terms of materials intrinsic resistance

28
Q

Resisitivity of conductors increases with what?

A

temperature

29
Q

When is Ohm’s Law obeyed?

A

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

30
Q

What is Ohm’s Law?

A

Voltage equals Current times Resistance

31
Q

What is a DC circuit?

A

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

32
Q

What terminal has higher potential in a DC circuit?

A

Positive terminal

33
Q

What terminal has lower potential in a DC Circuit?

A

Negative terminal

34
Q

Which direction does conduction electrons drift in a DC circuit?

A

low to high potential or negative to postive

35
Q

What is the direction of current in a DC circuit?

A

counterclockwise going negative to positive

36
Q

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

A

Current is the same and voltage is different

37
Q

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

A

Voltages are the same and currents are different

38
Q

What is Kirchhoff’s law dealing with voltage?

A

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.

39
Q

What is kirchhoff’s law dealing with current?

A

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

40
Q

What does power for resistors equal?

A

Power equals Current squared times resistance

41
Q

What is power dissipated by resistors equal to?

A

Power supplied by battery. conservation of energy

42
Q

What does power equal for a circuit?

A

Power equals Current times voltage

43
Q

What are voltmeters used for?

A

to measure the voltage between two points in a circuit

44
Q

What are ammeters used for?

A

Measure current through a particular point in circuit

45
Q

What is a galvonometer?

A

measures current using interaction between currents and magnetic fields

46
Q

What is a capacitor?

A

pair of conductors that hold equal but opposite charges

47
Q

What is the net charge of a capacitor?

A

zero

48
Q

What are the units for capacitance?

A

Faraday or Coulomb per volt

49
Q

What is capacitance determined by?

A

sizes of plates and how far apart they are

50
Q

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

A

greater

51
Q

What are the two uses for a parallel plate capacitor?

A

create a uniform electric field and store electric potential energy

52
Q

Electric Fields between capacitors always point in which direction?

A

positive to negative

53
Q

How is potential energy stored between plates?

A

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

54
Q

What does an insulator do for capacitance?

A

It increases

MCAT (46 decks)

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