NS-Term 3 - Unit 3: Series and parallel circuits pg 231-243

Question 1

What is an electric current?

Answer 1

It is the flow of charge

Question 2

What is charge?

Answer 2

It is the collective name for billions of electrons

Question 3

What are conductors?

Answer 3

Substances that conduct an electrical current

Question 4

What happens when a conductor heats up?

Answer 4

The conductor heats up and conduction of current is weaker (resistance increases)

Question 5

What do conductors do?

Answer 5

They offer little resistance against flow of charge

Question 6

What are conductors made of?

Answer 6

metals like copper, silver and iron

Question 7

what is the symbol for a connector?

Answer 7

________ ( a line)

Question 8

What happens during the flow of current?

Answer 8

During flow of current, electrons collide with particles of the conductor

Question 9

What happens when kinetic energy is transferred?

Answer 9

When kinetic energy is transferred, the conductor heats up and conduction of current is weaker (resistance increases)

Question 10

Define rheostat

Answer 10

adjustable resistance

Question 11

What is the unit of resistance?

Answer 11

ohm

Question 12

What is a resistor?

Answer 12

it is the component that can control the energy transfer in the current and convert it into useful forms

Question 13

Where does usable energy conversion take place?

Answer 13

in resistors like light bulbs, rheostats, cars, LEDs, appliances in the home

Question 14

Name the 4 factors that influence resistance

Answer 14

Type of conductor

• Metals like gold, silver and copper have low resistance
• tungsten, nickel and iron have high resistance

Length of conductor
- longer the conductor, greater the resistance

Thickness of conductor
- thicker the conductor, the smaller the resistance

Temperature
- hotter the conductor, greater the resistance

Question 15

How are light bulbs connected?

Answer 15

In parallel

Question 16

does the whole current flow through each light bulb? explain.

Answer 16

No. With parallel connections, there is more than one electrical path that can be followed.

Question 17

what happens if more resistors are connected in parallel?

Answer 17

If more resistors are connected in parallel, the total resistance in circuit decreases and the total current increases

Question 18

what is needed for an electrical current to flow?

Answer 18

a source of electrical energy is needed

Question 19

what direction does current flow and what is this called?

Answer 19

direction of current is from positive pole of the battery, through the circuit to the negative pole. this is called conventional current

Question 20

what is current measured with?

Answer 20

current is measured with an ammeter

Question 21

how is an ammeter connected?

Answer 21

in series

Question 22

what does potential difference mean and what is it measured with?

Answer 22

it is the difference in potential energy between 2 points. Symbol: V. always measured with a voltmeter

Question 23

give the formula to work out resistance

Answer 23

R= V/I

Question 24

what is the unit for resistance?

Answer 24

ohm

Question 25

do cells deliver constant current?

Answer 25

No, cells don’t deliver constant current

Question 26

do cells produce a constant current?

Answer 26

no, cells produce a constant potential difference not a constant current (current flows if circuit is closed)

Question 27

How many paths are there for current to flow through in series connection?

Answer 27

There is only one path for current to flow through all connections

Question 28

Is the current strength the same all over or does it differ?

Answer 28

the strength of current is the same all everywhere (potential difference over resistors is divided in the same ratio as resistance of each resistor)

Question 29

What happens when you add more resistors in series?

Answer 29

total current decreases with each resistor that is added in series

Question 30

what happens when you add more light bulbs in series

Answer 30

the more light bulbs (resistors) connected in series, the greater the resistance to current

Question 31

Is there more than one path for current to flow in parallel?

Answer 31

yes, there is more than one path for current to flow in parallel (there is a separate path through each component)

Question 32

Is potential difference the same all over or does it differ?

Answer 32

Potential difference is the same all over the parallel components (all parallel resistors have the same potential difference)

Question 33

What happens when you add more light bulbs in parallel circuit?

Answer 33

The more light bulbs (resistors) that are connected in, the less resistance.