Electricity & Magnetism

Question 1

Explain (in terms of electrons) how objects can become charged?

Answer 1

When you rub one object with another the electrons are transferred from one object to another meaning the object with extra electrons is now negatively charged and the object with less electrons is now positively charged.

Question 2

Explain how different charges interact (attract or repel)?

Answer 2

The same charges repel whereas opposite charges attract.

Question 3

What are particles atoms composed of?

Answer 3

Protons, electrons and neutrons
Go to Good Notes to label a diagram

Question 4

Explain where the charged electrons come from in a wire?

Answer 4

The charged electrons are already in the wire the battery just pushes them around the circuit.

Question 5

Distinguish static and current electricity?

Answer 5

In static electricity the charges aren’t moving whereas in current electricty they are

Question 6

Label the symbols for an electrical circuit and use the symbols to draw an accurate circuit diagram?

Answer 6

In Good Notes

Question 7

What is an electric field?

Answer 7

A region where a charged material or particle experiences a force.

Question 8

Compare a gravitational field and an electric field.

Answer 8

Gravitational fields can only produce forces of attraction, whereas electric fields can produce attraction and repulsion.

Question 9

What is meant by current? Recall the unit current is measured in?

Answer 9

The flow of electrical charge (electrons) around a complete circuit per second. It is measured in amps

Question 10

What is meant by potential difference (i.e. voltage)? How do you measure it?

Answer 10

A measure of the push of a cell or battery, or the energy that the cell or battery can supply. You can measure the potential difference of a cell by connecting a voltmeter across it in parallel. It is measured in volts

Question 11

Why is potential difference measured in parallel?

Answer 11

To measure the difference in energy from one side of the component to the other.

Question 12

Describe the differences between a series and parallel circuit?

Answer 12

In a series circuit there is only one loop whereas in a parallel circuit there is more than one.
If you add components in a series circuit the current will decrease whereas if you add a component in a parallel circuit the current will stay the same.

Question 13

Explain why current and potential difference vary in series and parallel circuits

Answer 13

Because in series there is only one path for the charged electrons to take so the voltage is shared between components whereas in parallel there are multiple paths so the potential difference is the same as the battery.

Question 14

Explain the causes of resistance

Answer 14

Collisions between the electrons and the atoms present in the conductor making it more difficult for the electrons to pass through.

Question 15

What would happen if a resistor was placed in circuit and explain why?

Answer 15

The current of the circuit would decrease because the resistor would slow down the flow of electrons and the components would lose some current.

Question 16

Compare the effect of resistance in different materials

Answer 16

Metals are conductors so they will be bad resistors as they have lots of electrons that can move. Plastics and wood are insulators so they will be good resistors as they don’t have many electrons that can move.

Question 17

What are the equations to calculate current (A) and Resistance (Ω)?

Answer 17

Resistance (Ω) = Potential Difference (V) / Current (A)

Question 18

How can magnets be used in everyday situations?

Answer 18

Magnets are used to keep things closed such as fridge doors.
Information on a credit card is stored on a magnetic strip.

Question 19

Name the 4 magnetic materials

Answer 19

Iron, steel, cobalt and nickel

Question 20

What happens when two like poles and two unlike poles of a magnet come together?

Answer 20

Like poles repel, unlike poles attract.

Question 21

What is a magnetic field? Draw a magnetic field for a bar magnet

Answer 21

A region where there is a force on a magnet or magnetic material.
Draw in GoodNotes

Question 22

How does a compass work?

Answer 22

A compass has a magnet inside of it so it lines up with the earth’s magnetic field because north is attracted to south which is at the top of the earth’s magnetic field.

Question 23

Describe how to make an electromagnet and explain it’s uses.

Answer 23

Wrap a piece of insulated wire around a iron nail and then connect the two ends of the wire to both ends of a battery.

Levitating trains use electromagnets to repel each other and push it forward.
X-rays have a large potential difference so can be dangerous so they are turned on with a relay.
A relay uses a small current in one circuit to charge an electromagnet which the attracts two pieces of iton and turns on a bigger circuit.
A car battery uses a relay to turn on and off.
To move lsrge pieces of iron or steel.
When you connect a coil to a battery current flows in the coil and it becomes an electromagnet and the force between the coil and the permanent magnet makes the coil spin.

Question 24

Predict the effect of changes on the strength of different electromagnets.

Answer 24

When you change the amount of coils around the nail it becomes stronger.
The current flowing in the wire. More current flowing in the wire will make a stronger electromagnet.
The type of core. Using a magnetic material in the core will make a stronger electromagnet.