Unit 5: Currents, Circuits, and Magnetism Flashcards

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1
Q

battery

A

an energy storage device that provides a constant potential difference (6V) between two locations (terminals) inside the battery

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2
Q

Current (I)

A

the flow of electric charge
convention system for current refers to positive charge, moving

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3
Q

Which way do electrons travel in a battery?

A

positive terminal to the negative (opposite of usual)

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4
Q

How does a battery work?

A
  • voltage is created when positive and negative charges are separated.
  • batteries are charged escalators that move positive charge from the negative terminal to the positive terminal
  • ## the battery is a source of voltage because the chemical reactions give potential energy to charge
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5
Q

Drift Velocity

A

electrons move slowly in the direction opposite of the electric field.

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6
Q

Direct Current (DC)

A

charge that moves in one direction only (battery)

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7
Q

Alternating Current (AC)

A

the voltage alternates from positive to negative so the output current from the generator changes its direction at regular intervals
- Charge that repeatedly reverses direction

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8
Q

Resistance (R)

A

the opposition to motion of charge (current) through a conductor

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9
Q

Factors that affect resistance (4)

A

-cross-sectional area
-material
-temperature
-length

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10
Q

Greater area/ thicker, (less/more) resistance

A

less resistance

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11
Q

copper, (less/more) resistance

A

less resistance

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12
Q

Iron, (less/more) resistance

A

more resistance

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13
Q

low temperature, (less/more) resistance

A

less resistance

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14
Q

high temperature, (less/more) resistance

A

more resistance

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15
Q

shorter wire length, (less/more) resistance

A

less resistance

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16
Q

longer wire length, (less/more) resistance

A

more resistance

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17
Q

Electric Power (P)

A

the rate at which electrical energy is converted into non electrical forces of energy like heat or light
(rate at which work is done)
-also known as wattage.

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18
Q

Electric Circuit

A

path through which charges can flow (bulbs, wires, resistors, batteries)

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19
Q

Open Circuit

A

no complete path -> no charge flow -> no current

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20
Q

Short Circuit

A

circuit with no load (no resistors, only wires) so very little resistance, or when an element is cut out of a circuit

21
Q

Series Circuit

A

When multiple components are connected in a single loop so all charge must follow a single path

22
Q

Series Equations

A

Itotal = I1 = I2 = I3 = …
Vbatt = V1 + V2 + V3 + …
Req = R1 + R2 + R3

23
Q

Complex Circuit

A

a combination of resistors within a circuit that includes both series and parallel arrangements

24
Q

The Req of a SERIES circuit is (smaller/larger) than the largest resistance in the circuit

A

larger Equivalent Resistance

25
Q

The Req of a PARALLEL circuit is (smaller/larger) than the smallest resistance in the circuit

A

smaller Equivalent Resistance

26
Q

Where in a PARALLEL circuit is there the most current?

A

where there is the least resistance

27
Q

Where in a SERIES circuit is there the most current?

A

current is the same everywhere in the circuit

28
Q

Parallel Circuit Equations

A

It = I1 + I2 + I3 + …
Vbatt = V1 = V2 = V3 = …
Req = 1/R1 + 1/R2 + 1/R3 …

29
Q

Magnetism

A

derived from electrons spinning on their axis; a charge in motion, which produces a magnetic field

30
Q

Magnetic domains

A

strong interaction between neighboring atoms to form large groups that have aligned fields
-unmagnetized materials have domains randomly oriented, with electrons in pairs going opposite directions

31
Q

How to demagnetize a material

A
  1. hammering the magnet
  2. heat or cool the magnet

this upsets the magnetic domain and repositions the electrons

32
Q

Magnetic Field

A

a region in which a magnetic force is detected
-produced by the motion of electric charges
-compass needle will align with the magnetic field lines

33
Q

Earth’s Magnetic Field

A

earth’s north is opposite to the geographic
- it’s generated by the movement of charges in the convection current
- it reverses often

34
Q

Solenoid

A

A long round coil of insulated wire
- acts like a bar magnet when carrying current
- magnetic field strength is proportional to the number of coils per length
- more coils, stronger fields

35
Q

Electromagnet

A

A solenoid with an iron rod through the center increasing the magnetic field; magnetized through circuits

36
Q

Electromagnetic induction

A

The process of induction of a current in a circuit without the power supply by changing the magnetic field that passes through the circuit
- magnet or circuit must be moving
- the separation of charges by the magnetic field induces a voltage

37
Q

Motors

A

Consist of a coil of wire between two magnets
- current is supplied to the loop by the battery and the magnetic force on the loop causes it to rotate
- converts electrical energy to mechanical energy

38
Q

Generators

A

Induces current by changing the orientation of the loop with respect to the magnetic field
- convert mechanical energy to electrical energy

39
Q

Transformers

A

Change a small alternating current applied voltage to a large voltage and vice versa

40
Q

Electromagnetic wave

A

Composed of oscillating electric and magnetic field that regenerate each other
- produced by accelerating charges

41
Q

in a typical/conventional electric circuit, electrical current is the flow of

A

Positive charge

42
Q

V (Volt) Unit break down

A

J/C

43
Q

A (Ampere) Unit break down

A

C/s

44
Q

O (Ohm) Unit break down

A

Js/C²

45
Q

Which has the greatest electrical resistance?
Dry skin, skin wet with tap water, skin wet with salty water

A

Dry skin

46
Q

A bird can perch harmlessly on bear high voltage wires because

A

All parts of the bird are at the same potential

47
Q

To prevent shock from occurring when touching an electrical appliance, the outside of the appliance is connected to the

A

ground

48
Q

A 50 ohm light bulb and a 100 ohm light bulb are connected in SERIES. Which is brighter?

A

the 100 ohm light bulb

49
Q

A 50 ohm light bulb and a 100 ohm light bulb are connected in PARALLEL. Which is brighter?

A

The 50-ohm light bulb