Chapter 5 - The Material World Flashcards

1
Q

What is electricity?

A

The movement of electrons from one body to another.

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2
Q

Can protons move out of the nucleus of an atom?

A

No, only electrons can move from one atom to another.

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3
Q

What does it mean if an object is positively charged?

A

It has lost electrons and has more protons than electrons.

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4
Q

What does it mean if an object is negatively charged?

A

It has gained electrons and has more electrons than protons.

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5
Q

What is the unit of measurement for electrical charge?

A

Coulomb (C). One Coulomb is equal to 6.25×10^18 electrons or protons.

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6
Q

State the Law of Electrical Attraction and Repulsion.

A

Like charges repel, and opposite charges attract.

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7
Q

What is static electricity?

A

The movement of electrons between objects at rest (not connected in an electrical circuit).

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8
Q

What are three ways to charge an object at rest?

A

Friction, conduction, and induction.

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9
Q

What happens when two objects are charged by friction?

A

Electrons are transferred, leaving one object positively charged and the other negatively charged.

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10
Q

How does the electrostatic series determine charge?

A

It ranks materials by how strongly they hold electrons. Materials with a stronger hold become negatively charged when rubbed.

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11
Q

What is an electrical field?

A

An area of space where the electrical force of a charged object can act on another charged object.

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12
Q

State Coulomb’s Law.

A

The electrical force between two charged objects depends on their charges and the distance between them. F_e = k * (q1 * q2) / r^2.

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13
Q

What two factors affect the force between two charges?

A

The strength of the charges and the distance between them.

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14
Q

If the distance between two charged particles is halved, how is the force affected?

A

The force is quadrupled, as it is inversely proportional to the square of the distance.

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15
Q

What is dynamic electricity?

A

The flow of electrons in a circuit.

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16
Q

In which direction do electrons flow in a circuit?

A

From the positive side of the battery to the negative side.

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17
Q

What is current intensity?

A

The number of charges that pass a given point in a circuit per second.

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18
Q

What is the unit of current intensity?

A

Amperes (A).

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19
Q

What device is used to measure current intensity?

A

Ammeter, which is connected in series.

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20
Q

What is the formula for current intensity?

A

I = q / Δt

I = current (A), q = charge (C), Δt = time (s)

21
Q

What is potential difference?

A

The difference in energy between two points in a circuit.

22
Q

What is the unit of potential difference?

A

Volts (V).

23
Q

What device is used to measure voltage?

A

Voltmeter, which is connected in parallel.

24
Q

What is the formula for potential difference?

A

V = E / q

V = voltage (V), E = energy transferred (J), q = charge (C)

25
Q

What is resistance?

A

The ability of a material to resist the flow of current.

26
Q

What is the unit of resistance?

A

Ohms (Ω).

27
Q

What happens when resistance increases in a circuit?

A

More energy is needed to push the current through (higher voltage required).

28
Q

What is the formula for Ohm’s Law?

A

V = I × R

V = voltage (V), I = current (A), R = resistance (Ω)

29
Q

What are the four factors that affect resistance?

A
  1. Nature of substance (conductor vs. insulator)
  2. Length of wire (shorter = less resistance)
  3. Diameter of wire (larger = less resistance)
  4. Temperature of wire (colder = less resistance)
30
Q

What is conductance?

A

The ability of electric charge to flow through a path (opposite of resistance).

31
Q

What is the unit of conductance?

A

Siemens (S).

32
Q

How does current intensity change when voltage increases in a circuit with constant resistance?

A

Current intensity increases (directly proportional).

33
Q

What happens to voltage if resistance increases but current stays the same?

A

Voltage increases.

34
Q

What is electrical power?

A

The amount of energy a device transforms in a certain amount of time.

35
Q

What is the unit of electrical power?

A

Watts (W).

36
Q

What is the formula for power?

A

P = I × V

P = power (W), I = current (A), V = voltage (V)

37
Q

What is the unit of electrical energy?

A

Joules (J) or kilowatt-hours (kWh).

38
Q

What is the conversion factor between kWh and J?

A

1 kWh = 3,600,000 J.

39
Q

What is the formula for electrical energy?

A

E = P × Δt

E = energy (J), P = power (W), Δt = time (s)

40
Q

What is a series circuit?

A

A circuit where electrons only have one path to follow.

41
Q

What is a parallel circuit?

A

A circuit where electrons have more than one path to follow.

42
Q

What happens to total resistance in a series circuit?

A

It is the sum of all individual resistances.

43
Q

What happens to total resistance in a parallel circuit?

A

It is the reciprocal sum of individual resistances.

44
Q

What does Kirchhoff’s Current Law (KCL) state?

A

The sum of currents entering a junction equals the sum of currents leaving the junction.

45
Q

What does Kirchhoff’s Voltage Law (KVL) state?

A

The sum of the voltage drops across resistors equals the sum of the voltage rises (from a battery) in a closed loop.

46
Q

How does current behave in a series circuit?

A

It stays the same throughout the circuit.

47
Q

How does voltage behave in a series circuit?

A

It adds up: V_t = V_1 + V_2 + V_3.

48
Q

How does current behave in a parallel circuit?

A

It adds up: I_t = I_1 + I_2 + I_3.

49
Q

How does voltage behave in a parallel circuit?

A

It stays the same: V_t = V_1 = V_2 = V_3.