P3 - Electricity

Question 1

What charges do protons and electrons have?

Answer 1

Protons have positive charge

Electrons have negative charge

Question 2

What are the charges of the three subatomic particles ?

Answer 2

Protons - +1 charge = mass of 1
Neutrons - 0 charge = mass of 1
Electrons - -1 charge = mass of 0.0005

Question 3

Why is an atom neutral?

Answer 3

Same number of protons and electrons

Positives and negatives cancel our

Question 4

How do we generate static charge?

Answer 4

Electrons are moving
If two insulators are rubbed, electrons get transferred from one insulator to the other.

Therefore one insulator is going to have more electrons than protons - negatively charged
Vice versa

Question 5

How can we discharge an object?

Answer 5

Connect the object to piece of metal meaning charges can flow therefore object becomes discharged

Spark - flow of current through the air.

Question 6

What is current?

Answer 6

The rate of flow of charged particles which are the electrons.
Cell , battery or power supply is need to make current flow as well as a complete circuit

Question 7

Explain the current in a single closed loop?

Answer 7

Current is going to be the same anywhere

Question 8

What is the formula for charge flow?

Answer 8

Charge flow (C) = current (A) * time (S)

Question 9

What is potential difference?

Answer 9

Required for the current to flow in a circuit.

Caused by the separation of charges inside the cell or battery

Question 10

Which terminal had a higher electrical potential?

Answer 10

Positive charge has a higher electrical potential than the negative charge

Question 11

How is potential difference measured?

Answer 11

Using a voltmeter

Volts

Question 12

Which lines is the positive and negative terminal

Answer 12

Positive terminal - longer lines

Negative terminal - shorter lines

Question 13

What happens when we apply potential difference between ends of a wire?

Answer 13

Electrical fuels is being set up

Question 14

What is the formula for energy transferred?

Answer 14

Energy transferred (J) = potential difference (V) * charge (C)

Question 15

Explain the series circuit?

Answer 15

• current is the same everywhere

- work out the current using ammeter

Question 16

If we wanted to know pd what do you do?

Answer 16

Place a voltmeter in parallel circuit

Question 17

Explain series circuit in terms of reading volt meters?

Answer 17

The reading on all voltmeters across the components is equal to the reading across the battery.

Question 18

Explain parallel circuit in terms of current?

Answer 18

The current in all the loops adds up to the current near the battery.
The pd across each component is the same as across our battery

Question 19

How can you troubleshoot it your light doesn’t light up?

Answer 19

• connect bulb to the battery
• if doesn’t work try another battery
• if doesn’t work try another bulb
• replace single wire at a time until all wires are checked

Question 20

What does current depend on?

Answer 20

• Potential difference And resistance in the circuit
  Resistance is measure in ohms.

Current is dependent variable , so we can only change it by changing pd or resistance.

Question 21

What is ohms law?

Answer 21

Current is proportional to the potential difference if the temperature does not change

Question 22

Why does the resistance of some components change?

Answer 22

Metal is made up of positively charged ions arranged in a regular pattern. The outer shells has lost some electrons which have become delocalised.
Because they’re delocalised, free to move.
When delocalised electrons collide with metal ions , resistance is produced.

Question 23

Explain resistance in wires.

Answer 23

Thinner wires or longer wires = greater resistance because greater chance of electrons colliding with the positive metal ions.
Thicker wire = lower resistance

Question 24

What is a variable resistor?

Answer 24

Change the resistance … changing amount of current that then can flow through the circuit.

E.g. dim switches. Twisting means changing the number of coils of the wire that the current is actually flowing through therefore changing resistance.

Question 25

What is a characteristic graph

Answer 25

Current plotted against potential difference.

Question 26

What is a linear circuit element

Answer 26

Component that has a resistance that does not change. E.g. fixed resistor

Identify by straight line

Question 27

What is a non linear circuit element ?

Answer 27

Component that has a resistance that does change.
E.g. lamp

Not a straight line so resistance is changing.

As the electrons collide with the metal ions in the wire, the ions vibrate more. This makes the wire get hotter.

Question 28

What is a diode and explain the circuit graph?

Answer 28

Divides only let current flow one way,

Only flow one way so no negative.