# Chapter 18 Flashcards

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1
Q

Battery

A

Produces constant voltage to make charges move (current)

1. Electrons free to move in conductors → carry energy through circuit.
2. Energy comes from a battery (converts chemical → electrical energy)
3. As energy is transformed, a potential difference V develops across the battery’s terminals (called EMF).
2
Q

Current

A

amount of charge that passes through an area in a given amount of time

units: Amps → (1A = C/s)

3
Q

Equations for current (I)

A
4
Q

Current in a metal wire is proprotional to what?

A

Current (I) proportional to potential diff (V) applied to its 2 ends

5
Q

Electrode

A

6
Q

Electrolyte

A

solution (ie a dilute acid)

7
Q

Terminal (battery)

A

part of electrode outside of solution (where you connect wires/circuits)

8
Q

What is the simplest BATTERY made of?

A

2 electrodes (+ and –) & 1 electrolyte

9
Q

Ciruit

A

continuous conducting path connected between terminals of a battery

10
Q

Complete Circuit

A

continuous conducting path

11
Q

Open circuit

A

break in circuit (ie. cut wire)

12
Q

Ground

A

common conductor (provides continuity)

13
Q

Conventional current

A

current direction in a circuit = direction + charge would flow

14
Q

Resistance

A

opposition to flow of charge

units: ohms → (1 Ω = 1 V/A)

15
Q

In a device that produces heat (ie. toaster) what kind of resistance do you want?

A

HIGH resistance needed (otherwise no heat produced)

16
Q

Do you want low/high resistance in wires?

A

LOW resistance wires (to minimize energy loss)

17
Q

Resistance of a uniform wire EQUATION

A

p = constant of proportionality (RESISITIVITY) → units (Ω m) → depends on material used

18
Q

A

It has the lowest resistivity (p), therefore lowest resistance (R) making it best conductor → electrons free to move

19
Q

Ohm’s Law EQUATION

A

V = IR

20
Q

To what materials can Ohm’s law be applied?

A

Ohmic materials: metal conductors (R is constant) whose temperature doesn’t change much

21
Q

What are resistors used for?

A

used to control (reduce) the amount of current in a circuit

22
Q

What factors does resistance depend on?

A

type of material wire made of, length, cross sectional area

23
Q

Electrical conductivity

A

amount of current a material can carry

(reciprocal of resistivity)

24
Q

Electrical conductivity EQUATION

A
25
Q

How does temperature effect resistance?

A

R of metals INCREASES at higher temp

(because atoms move faster and interfere more with flow of electrons)

26
Q

Power

A

amount work down / time

rate energy is transformed

27
Q

Power EQUATIONS

A

P = IV

P = W/t

28
Q

Do thicker wires have less or more resistance?

A

less R

29
Q

Fuses/circuit breakers

A

switches that open the circuit when current exceeds a safe value to prevent overloading

30
Q

Open circuit

A

no longer a complete conducting path (no current can flow)

as if R = infinity

31
Q

Short ciruit

A

two wires touched that shouldn’t have

32
Q

Q: Why shouldn’t properly rated fuses be replaced by higher-rated ones?

A

Fuse won’t blow as intended and high current will harm (ie. melt) whole circuit…

33
Q

Direct Current (DC)

A

one-directional flow of electric charge

(battery example)

34
Q

Alternating current

A

reverse direction many times/sec (sinusoidal)

35
Q

Rectifier

A

AC → DC current

36
Q

Inverter

A

DC → AC