Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Basics > Electrostatics > Flashcards

Electrostatics Flashcards

1
Q

Electric charge

A

Describes a body related to an electric field. May be positive or negative. Bodies with like charges repel each other, while those with unlike charges attract.

Unit: Coulumb

Always linked to other bodies because it. cannot exist on it’s own.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Most important charge carrier

A

The electron with a charge of -e

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Charge carriers

A

particles with electric charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Elementary charge

A

e=1,6*10^-19

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does it mean that the electric charge is a discrete physical value?

A

It cannot assume any value. The electric charge of a body can only be the integer of the elementary charge.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Proton

A

Has a charge of e+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Cation

A

A positive ion formed from a neutral particle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Anion

A

A negative ion formed from a neutral particle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Coulomb’s law

A

The force law of electrostatic interaction, gives the force acting between two electrically charged point-like bodies. It’s an inverse square law, as is the gravitational force.

F= k* (q1*q2)/r^2

k=9*10^9 Nm/C^2

r^2 is distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What keeps the negative electrons around the positive atomic nucleus?

A

Couloumbs force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Electric field

A

a model for understanding the electric interaction which helps to imagine how two bodies act on each other even if they are far away

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Field lines

A

Used to visualize the force field. The direction of a field line in a given point gives the direction of the force acting on the positive test charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The magnitude of a force field can be described by the…

A

density of the field lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Homogenous/uniform electric field

A

the positive test charge has the same strength(magnitude) and the same direction at each point.

Field lines are parallel and density is uniform.

E.G The electric field between the plates of a capacitor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Inhomogenous electric field

A

Field lines may have different magnitude and different direction.

E.g: The electric field of a point like charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Electric dipole

A

two charges of equal magnitude but opposite sign (+q and -q) at a given distance. Electric field of this arrangement is inhomogeneous (dipole field).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Electric dipole moment

A

Gives the strength of a dipole

P = q*d

Unit= coulomb*meter or debye

18
Q

Which weird molecule has an electric dipole moment?

A

H2O

electrons are not uniformly distributed due to high electronegativity of oxygen.

The electric field of the heart can be described with a dipole field.

19
Q

Electric field strength

A

E= F/q

Unit: N/C or V/m

A vector quantity

Is uniform (the same everywhere) in an homogenous electric field.

20
Q

Voltage

A

also called electric tension

The work needed to move a unit charge
Unit: Volt
U21= W/q

We assume we work against the electric field in this formula, and the work will be positive. U21 refers to two positions in electric field. Point #2 is at higher potential than #1, work is going from point 1 to point 2.

21
Q

How does voltage characterize field strength?

A

If the field strength is greater, more work must be done, and the voltage between the two points must be greater as well.

22
Q

Resting potential/voltage of a cell

A

-100mV

field points in the direction of the interior of the cell
charge moves from exterior to interior -> hence the negative sign.

23
Q

Electric potential

A

the voltage between two points is equal to the differences between their electric potentials.

24
Q

Equipotential surface

A

The set of all points which have the same electric potential value.

Electric field lines crosses equipotential surfaces at a right angle at every point of the electric field.

25
Q

Capacitor

A

An electrical component capable of storing electric charge and energy as well as creating homogenous electric field. Charging a capacitor gives one plate a positive charge and the other side a negative charge.

26
Q

Parallel plate capacitor

A

The simplest form of a capacitor. Two parallel metallic plates with vacuum or some other insulating material between them.

27
Q

Electric field strength of the capacitor

A

E=U/d

Unit: V/m or N/C

Electric charge and voltage is proportional to each other.

28
Q

Capacitance

A

The proportionality between the electric charge and the voltage.

Unit: Farad (C/V)

Measure of the charge-storing ability of a capacitor which gives the charge stored in the capacitor if its voltage is 1 V.

29
Q

What does the capacitance depend on?

A

The dimensions of the capacitor.
- the greater the surface area of the plates, the more charge it can store at a given voltage

-the lower the distance between the plates, the stronger the field and the more charge required to maintain a given voltage

C= E0Er(A/d)

E0= absolute permittivity of vacuum, 8,85*10^-12
Er= the relative permittivity of the insulating medium between the plates
30
Q

Charging of capacitor

A

Both plates are neutral and one electron is moved from one plate to the other. The plates are now charged. Every electron moved the same way will require more work put in.

31
Q

The electric energy stored in the capacitor

A

The work needed to charge the capacitor which is stored as energy in the electric field of the capacitor. The more charge is transferred to the plates of the capacitor, the stronger the electric field and the greater the energy.

W= 0,5(q^2/C) = 0,5C*U^2

32
Q

Connecting capacitors in series

A

C= C1+C2+C3+…

33
Q

Connecting capacitors in parallel

A

1/C=1/C1+1/C2+1/C3+…

34
Q 
(PP) We double the distance between two electrons. How will the repulsive force acting between them change?
A) It doubles
B) It decreases by half
C) It increases four times
D) It decreases to its fourth
A

B?

35
Q

(PP) How can we obtain the resting potential of a cell?
A) By measuring the electric current between two points
B)By measuring the change in resistance between the two points
C) By measuring the conductance between the two points
D) By measuring the voltage between two points

A

D

36
Q 
The voltage between the plates of a capacitor is increased by 100%. How does the capacitance change?
A) It does not change
B) Increases by 50%
C) Decreases by 50%
D) Increases by 100%
A

D

37
Q

A 20ohm resistor is connected to a 100 V voltage source. Which of the following statements is correct?
A) The electric power is 2 MW
B) The electric power is 0,5W
C) The current flowing through it is 200 A
D) The current flowing through is 5 A

A

A

38
Q 
(PP) What is the Coulomb force acting between two electrons if the distance between them is 0,18 nm?
A) 1,28 aN
B) 7,11 nN
C)7,11 fN
D)44,4 GN
A

B

39
Q

(PP) The voltage between two points of the same equipotential surface…

A) Is proportional to the distance between the two points
B) Is inversely proportional to the square of the distance between the two points
C) Is always zero
D) Is a positive number

A

C

40
Q

(PP) In an electric field
A) the direction of electric field lines shows the direction of electric force acting on any point charge
B)…the density of electric field lines is proportional to the velocity change of the charged particle placed in the force field
C)…a symmetric pattern of electric field lines indicates a homogenous field
D)… the density of electric field line is uniform only if the field is inhomogeneous

A

C

41
Q

What is not true for electric charges?
A) it cannot exist in itself, only connected to a particle with a mass
B) it can create both attractive and repulsive forces
C) it can be positive or negative
D) electric charge is a quantity that does not have a least value, it can be divided indefinitely

A

D

42
Q 
A 20 kOhm resistor is connected to a 100 V voltage source. What is its conductance?
A) 0,2 S
B) 5 mS
C) 50 mS
D) 200 S
A

D

I = G*U

Basics (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions