Quiz #2 Electric Forces and Fields Flashcards

1
Q

What is an electric field?

A

A region of influence surrounding an object with charge.

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2
Q

How is the direction of an electric field determine?

A

PLacing a small positive test charge in the electric field and identifying the direction of the electrostatic force acting on the test charge.

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3
Q

What is a test charge?

A
  • The object that experiences influence in an electric field
    -Needs to have a small charge and not necessarily a small mass
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4
Q

What are the units for electric field? What does this unit mean?

A

N/C. Describes the force (in N) exerted on 1 unit of charge(how much influence 1 charge has)

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4
Q

h

A

n

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5
Q

What is electric potential energy?

A

Ep
It is the energy of a charged object due to its position in an electric field.

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6
Q

What happens to electric potential energy when work is done against the direction of the electric field?

A

Ep increases
(delta) Ep>0

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7
Q

What happens to electric potential energy when work is done in the same direction as the electric field?

A

Ep decreases
(delta) Ep<0

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8
Q

What happens to electric potential energy when motion is perpendicular to the direction of the electric field?

A

No change in Ep
(delta) Ep = 0

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9
Q

The work done by an applied force to move a charge in the electric field ___________(1) can be determined using the _____________(2). It is equal to ____________(3) when the object is moving at a constant velocity in a frictionless environment.

A

(1) At a constant velocity
(2) Work-Energy theorem
(3) Electric potential energy

Need to remember to write out the entire work-energy theorem and then cross out the parts o the equation by making sure that the object is moving at a constant velocity in a frictionless environment.

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10
Q

What is electric potential difference?

A

(delta) V

A measure of the work required to move a unit of charge a specific distance in an electric field. Also referred to as voltage

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11
Q

When is electric potential difference when moving perpendicular to the electric field?

A

Zero

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12
Q

What is a parallel plate? How is it created?

A

Designed to produce a uniform electric field in the region between the plates. A battery is hooked up to two metallic plates. The battery will do work to build a negative charge of -q on one plate and leave the opposite plate with a positive charge of +q.

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13
Q

What is the purpose of the Millikan Oil Drop Experiment

A

To determine the magnitude of charge on an oil drop. Each drop is whole number multiple of a base unit of charge.

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14
Q

___________(1) is a factor in the motion of the oil droplet

A

(1) gravity

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15
Q

How does the apparatus for a Millikan Oil Drop experiment operate?

A
  1. An atomizer sprays charged oil droplets into the electric field.
  2. The voltage is adjusted until there is no motion of the drops in the vertical direction.
15
Q

How does the apparatus for a Millikan Oil Drop experiment operate?

A
  1. An atomizer sprays charged oil droplets into the electric field.
  2. The voltage is adjusted until there is no motion of the drops in the vertical direction.
16
Q

What is electric current?

A

The amount of charge moving past a specific point In a conductor over a certain time interval

17
Q

What is electric current abbreviated with?What is electric current measured in?

A
  • Electric curent is abbreviated with the letter I
  • Measured in unit of Amps(A)
    1.0 A = 1.0 C/S
18
Q

What is resistance? What is resistance measured in?

A

Resistance(R) limits the current that flows from a specific potential difference. Resistance exists even in good conductors. Resistance is measured in units of Ohms(horseshoe)

19
Q

What are the four factors that resistance is dependant on?

A
  1. Length of the conductor(L)
  2. Cross-sectional area of the conductor(A)
  3. The temperature of the conductor
  4. The nature of the material
19
Q

What is Ohm’s law?

A

describes the relationship between potential difference, electric current, and resistance.

(delta) V = IR

20
Q

How does resistance vary with L?

A

Resistance varies directly with L

21
Q

How does resistance vary with A?

A

Resistance varies inversely with A

22
Q

What happens to resistance as temperature increases?

A

Resistance increases as temperature increases

23
Q

What is material resistivity dependant on?

A

Material resistivity(p) is dependant on temperature

24
Q

What formula relates resistance with p, L, and A?

A

R = (pL/A)

25
Q

What is electric power?

A

The rate at which electric potential energy is dissipated by a resistor

26
Q

What are the two formulas needed to be memorized relating to electric power?

A

P = I (delta)V
P = I^2 R
P = (lql V)/ t

27
Q

What is conventional current?

A
  • Charges move from the positive terminal(area of excess charge) to the negative terminal(area of deficit charge) of a battery
  • Protons move from positive to negative terminal of a battery
  • Ask where a proton would move
28
Q

What is electron flow?

A

Electrons move from negative to positive terminal of a battery.

29
Q

The electric field anywhere inside of a conducting object is ________(1) even if the object is hollow.

A

zero

30
Q

For irregularly shaped conductors, the charge density will be greater on ___________(1) of the conductor and lower on __________(2) of the conductor.

A

(1) sharp edges
(2) flatter parts

31
Q

What are equipotential lines?

A

Lines of constant electric potential or voltage. They are always perpendicular to electric field lines.

32
Q

Electric fields are referred to as ____________(1) because they communicate information regarding both __________(2) and _____________(3) of the field. Equipotential lines are referred to as ____________(4) because they only communicate information regarding _____________(5).

A

(1) vector fields
(2)magnitude
(3) direction
(4) scalar fields
(5) magnitude