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Science 6 > Electricity : Chapter 1 - Section 2 > Flashcards

Electricity : Chapter 1 - Section 2 Flashcards

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1
Q

What is electrical energy?

A

Electrical energy is the energy of electric charges.

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2
Q

What is the electric current?

A

The electric current is the rate at which charges pass a given point.

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3
Q

What is electric current measured in?

A

Electric current is measured in amperes.

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4
Q

True or False : The higher the current is, the greater number of charges that pass the point each second.

A

True.

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5
Q

What is the symbol for amperes?

A

The symbol is A.

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6
Q

How does a flashlight light up?

A

When you flip a switch on a flashlight, an electric field is set up in the wire at the speed of light. Then, the electric field causes the free electrons in the wire to move. The energy of each electron transfers to the next electron instantly.

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7
Q

True or False : An electric field is like a command to electrons to charge ahead.

A

True. (all electrons obey command at same time)

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8
Q

What are the two kinds of current?

A

Alternating current and direct current.

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9
Q

What is AC?

A

Alternating current. In AC, charges continually shift from flowing in one direction to flowing in the reverse direction.

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10
Q

What is DC?

A

Direct current. In DC, charges always flow in same direction.

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11
Q

Which type of current gives energy to camera batteries?

A

DC.

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12
Q

Which type of current gives energy to outlets?

A

AC.

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13
Q

True or False : In the U.S. AC change direction 120 times a second (60 cycles a second)

A

True.

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14
Q

What is voltage?

A

Voltage is the potential difference between two points (measured in volts).

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15
Q

What is voltage measured in?

A

Volts. (V)

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16
Q

True or False : Voltage is not a measure of how much work is needed to move a charge between two points.

A

False. Voltage is a measure of how much work is needed to move a charge between two points.

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17
Q

True or False : Higher voltage is, more energy released per charge.

A

True.

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18
Q

True or False : As long as there is voltage between two points on a wire, charges will flow in the wire.

A

True.

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19
Q

True or False : As long as there is voltage between two points on a wire, charges will flow in the wire.

A

True.

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20
Q

True or False : The size of the current depends on voltage.

A

True

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21
Q

True or False : Smaller current means more charges move in the wire each second.

A

False. Greater current means more charges move in the wire each second.

22
Q

True or False : Large current needed to start a car (so the battery has fairly high voltage).

A

True.

23
Q

True or False : Things running on battery need high voltage.

A

False. Things running on battery need low voltage.

24
Q

True or False : Electrical outlets in the U.S. usually supply AC at 120 V, so most electrical devices made to run on 120 V.

A

True.

25
Q

True or False : Electrical outlets in the U.S. usually supply AC at 120 V, so most electrical devices made to run on 120 V.

A

True.

26
Q

What is resistance?

A

Resistance is the opposition presented to the current by a material or device.

27
Q

True or False: Resistance expressed in ohms (symbol for ohms: Ω and symbol for resistance: R).

A

True.

28
Q

True or False : The higher resistance of material, the lower the current of the material is.

A

True.

29
Q

True or False : As resistance goes up, the current goes up as well.

A

False. As resistance goes up, the current goes down.

30
Q

What four things does an object’s resistance depend on?

A

An object’s resistance depends on it’s material, thickness, length and temperature.

31
Q

True or False : Good conductors (like copper) have low resistance.

A

True.

32
Q

True or False : Poor conductors (like iron) have high resistance.

A

True.

33
Q

True or False : Resistance of insulators so high that electric charges cannot flow in them.

A

True.

34
Q

True or False : High resistance materials used for things like filaments in lightbulbs.

A

True.

35
Q

True or False : The atoms vibrate slower at a higher temperature and get in the way of flowing electric charges.

A

False. The atoms vibrate faster at a higher temperature and get in the way of flowing electric charges.

36
Q

What are superconductors?

A

Superconductors are materials in which there is very little heat and no resistance.

37
Q

True or False : Very little energy is wasted when electric charges move in a superconductor; however a large amount of energy is needed to cool them.

A

True.

38
Q

True or False : Very little energy is wasted when electric charges move in a superconductor; however a large amount of energy is needed to cool them.

A

True.

39
Q

True or False : Energy cannot be created or destroyed, only made into other types of energy.

A

True.

40
Q

True or False : Cells are devices that produce an electric current by converting chemical or radiant energy into electrical energy.

A

True.

41
Q

How many cells are batteries made up of?

A

One or more.

42
Q

What does a cell contain?

A

A cell contains a mixture of chemicals called electrolytes (allows chemicals to flow).

43
Q

What is an electrode?

A

The electrode is the part of a cell through which charges enter or exit.

44
Q

True or False : Chemical changes between the electrolytes and electrodes convert chemical energy into electrical energy.

A

True.

45
Q

What are the two kinds of cells?

A

Dry cells and wet cells.

46
Q

What are dry cells?

A

Dry cells have solid or paste-like electrolytes (used in small radios).

47
Q

What are wet cells?

A

Wet cells have liquid electrolytes (used in a car battery) .

48
Q

What are thermocouples?

A

A device that converts thermal energy into electrical energy.

49
Q

True or False : Thermocouples do not actually generate that much energy (most useful for monitoring temperature of car engines, furnaces and ovens).

A

True.

50
Q

What are photocells?

A

A device that converts light energy into electrical energy.

51
Q

True or False : Most photocells contain silicon atoms.

A

True.

52
Q

True or False : As light shines on the photocell, electrons gain enough energy to move between atoms; electrons then able to move through a wire to provide electrical energy to power a device (like a calculator).

A

True.

Science 6 (5 decks)

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