2.3 Electricity 1

Question 1

What is the difference between a conductor and an insulator ?

Answer 1

The difference between a conductor and insulator is how the electrons are distributed and how they move

Question 2

What are conductors like in terms of free electrons

Answer 2

In a conductor the electrons are free to move and carry charge

Question 3

What are the electrons like in an insulator ?

Answer 3

In an insulator the electrons are in shells on the atom so are not free to move and carry charge

Question 4

What is an electric current

Answer 4

An electric current is the flow of electrons.

Question 5

What is a conventional current?

Answer 5

• It flows opposite to electron flow
• It starts at positive and moves to negative

Question 6

How is the current measured ?

Answer 6

This is carried out using an ammeter, when connecting into a circuit the red (+) side should be on the same side of the circuit as the positive side of the battery.

Question 7

How are the components in a series circuit connected ?

Answer 7

In a series circuit the components are connected one after another and the electricity can only follow one path

Question 8

Where do you always draw the battery or cell in a series circuit ?

Answer 8

At the top

Question 9

How are the components connected in a parallel circuit?

Answer 9

In a parallel circuit the components are connected on different branches of the same circuit and the electricity has a choice of where to go

Question 10

What does an ammeter measure and what are the units

Answer 10

It measures current and the unit is amps

Question 11

Which side of the battery is positive?

Answer 11

The longer side

Question 12

What type of circuit should always have an ammeter connected ?

Answer 12

Series circuit

Question 13

What is electric charge measured in ?

Answer 13

Electric charge is measured in coulombs (C)

Question 14

When there is a complete circuit, how many electrons pass through the component and cell every second ?

Answer 14

Millions of electrons pass through the component and cell every second

Question 15

What is the size of an electric current?

Answer 15

The rate of flow of electric charge

Question 16

What is the relationship between charge and current ?

Answer 16

Q = I x T
Charge = Current x Time

Question 17

What is voltage ?

Answer 17

A battery or cell gives energy to the charge as it passes through it and the ability of the cell or battery to do this is called the voltage (potential difference)

Question 18

How do you work out the total voltage of cells in a series circuit?

Answer 18

When connected in series the total of each cells is added to together

Question 19

What is the equation of ohms law ?

Answer 19

Voltage = Resistance x Current
V = I x R

Question 20

What’s another name for voltage ?

Answer 20

Potential difference

Question 21

What is ohms law in words ?

Answer 21

Voltage and current are directly proportional given that the temperature is constant

Question 22

What is resistance?

Answer 22

The amount that a material will resist the flow of electrons

Question 23

What are voltage-current graphs used to investigate?

Answer 23

Can be drawn to investigate the resistance of a component

Question 24

What does the slope of a voltage - current graph tell you ?

Answer 24

The steeper the slope the higher the resistance

Question 25

How would you measure the current and voltage of the filament bulb ?

Answer 25

- Set the power supply to 6 V - Obtain six readings of current and voltage by changing the slider on the variable resistor and record them in a table (try to get a good range up to 3 V on the voltmeter) - Draw a current - voltage graph - Measure the resistance at different points by using Rise/Run

Question 26

Explain the graph for the filament lamp in terms of current, resistance and temperature?

Answer 26

- The electrons move at high speeds and collide with metal ions - The resistance increases because of the collisions - The high temperature increases the resistance

Question 27

What happens with current in a series circuit?

Answer 27

The current is the same at every point and so all ammeters in a series circuit will read the same value

Question 28

Why is the current the same at each point in a series circuit?

Answer 28

This is because current is the flow of electrons and because the electrons pass through each component. The same number of electrons pass through each component each second, meaning the current must be the same

Question 29

Where do you get the total voltage value in a series circuit?

Answer 29

The total is always from the battery

Question 30

What is the rule for voltage in a series circuit?

Answer 30

The voltage across each component in a series circuit is added together to get the total voltage from a power supply

Question 31

What are the rules for series circuits regarding voltage and current?

Answer 31

Current - is the same throughout each component, same throughout Voltage - splits across the components

Question 32

What happens to the current in a parallel circuit ?

Answer 32

The total current through the whole circuit is the sum of the current through each branch

Question 33

What happens to the voltage in parallel circuits?

Answer 33

The voltage is the same across branches The voltage across each branch is the same as the total voltage from the power supply

Question 34

What are the rules for parallel circuits regarding current and voltage?

Answer 34

Current - splits across the branches Voltage - stays the same across branches and is the same as the total voltage

Question 35

How do you always connect a voltmeter in a parallel circuit?

Answer 35

Always connect the voltmeter in parallel in the circuit