Electromagnetism

Question 1

Number one rule of charges

Answer 1

1.Like chargers repel each other
2.Opposite charges attract each other

Question 2

what do objects with charge produce ?

Answer 2

an electric field

Question 3

Electric field lines show what ?

Answer 3

• they show the direction of force(using arrows)
• Strenth of force (using density of lines)

• always draw these lines away from the positive charge as shown in the diagram
• For negative charges the lines points torwads the negative
• if close to the positive charger or denser length of the field lines there will a stronger electrical field

Question 4

The interaction of Negative and positive charges electric fields

Answer 4

Always away from the positive
torwards the negative

Question 4

Force on charges in an Electric field

Answer 4

• positive charges feel a force in the direction of the field lines
• Negative charges feel a force opposite the direction of the field lines

Question 5

The Definition Of ELECTRIC FIELD STRENGTH

Answer 5

the strength of the electric field is a measure of the force the field applies per unit of charge

Question 6

COLoumb’s Law on how to get the force REquired for Calculation of the gravitational field.

Answer 6

Question 7

For calculations of elecrtic field for two diffent charges remember

Answer 7

the force remains the same cause newtons third law says there is an equal and opposite reaction for every action

Question 8

Producing a uniform electric Field

Answer 8

The electric field between two charged parallel plates is found by

Question 9

Electric Field

Answer 9

1.Created by a charge
2.Pushes positive charges in the direction of the field
3.+ve charges gain electrical potential Energy when moved against the field (work done against the Field)
4.Ep Is converted into Kinetice Energy when +ve charge moves with the field (work done by the field)

Question 9

Electrical Potential Difference(Voltage) formula

Answer 9

Question 10

Final Kinetic energy for Particle in electromagnetism

Answer 10

1.Calculate the work first using the formula above
2.FInal Kinetic energy =Initial Kinetic energy -Work done
3.Ignore the numbers

Question 11

Potential difference in an electrical field

Answer 11

1.V=W/Q
2.W=Vq

Question 11

In W=Vq what is an eV(electron Volt)?

Answer 11

The energy gained by an electron movin across a 1.00V potential Difference

1.6x10^-19 J=1eV

Question 12

Commit this to memory

Answer 12

Question 12

Remember the curves lines on the edge of the plates!

Answer 12

Question 13

Work in an electric field

Answer 13

If the charged object is moving in the direction it would naturally go in the field, the work is being done by the field.

If it is moving against the natural direction, the work is being done on the field.

If it is moving perpendicular to the field, no work is being done.

Question 14

the more charge the object has …

Answer 14

The more work we had to do to change its location

Question 15

Electric work

Answer 15

W=Vq =qEd

q = the amount of substance affected by the field
E = electric field strength
d = the change in location

Question 15

Earths Magnetic field

Answer 15

If It's In the Northern Hemisphere the field Is DECLINED If in The Southern Hemisphere the filed IS INCLINED

Question 15

LIST three changes that can make an electromagnet More Effective

Answer 15

Question 16

Explain how an electron could be responsible for the magnetical behavour of a material

Answer 16

a movng charge like a Electron creates a magnetic Field.Certain Magnetic behaviour because of the orbting electrons producing magnetic fields that combine to produce larger Mag fields that extend beyond the structure of the material

Question 17

ELECTROMAGNETIC FIELDS IN A LONG WIRE,LOOP AND SOLENOID

Answer 17

Important

Question 18

Parts of A Motor

Answer 18

Important memorise this

Question 19

why does an electric motor rotate

Answer 19

There is an external magnetic field provides by a permanent magnet or an electromagnet(field coils)

the current is always perpendicular to the magnetic field.

F=NILB were
N=umber of coils where
=force ,
I=current,
L=length of the rotor coil perpendicular to B (m)
B= Magnetic flux density

Question 20

Calculations

Answer 20

Question 20

Faraday’s Law

Answer 20

a changing Magnetic flux through a loop will induce an EMF

Question 21

how to caluculate the Average Flux measured by the voltmeter on a coil’s movement and determine its direction

Answer 21

1.Calculate the flux(wbs) 2.the use the flux to calculate the induced emf through the formula in the pictures(V)

Question 22

lenz’s Law

Answer 22

1.A changing magnetic flux induces an EMF(FARADAY’LAW)
2.The Induced EMF drives a current
3.The induced current creates a magnetic field
4.The newly formed magnetic field has a direction that opposes the changing magnetic flux(Lenz’s law)

Question 23

FARADAY’S LAW CONTINUED

Answer 23

ALL OF THE QUANTITIES ARE PERPENDICULAR TO EACH OTHER

Question 23

please note

Answer 23

change in flux creates an EMF and an EMF creates A current that CREATES ITS OWN MAGNETIC FIELDS (FARADAY’S) (INDUCED FIELD PUSHES BACK)

Question 24

GUIDE TO ANSWERING FARADAY’S LAW QUESTIONS

Answer 24

Question 25

GUIDE TO ANSWERING FARADAY’S LAW QUESTIONS 2

Answer 25

Question 26

alternitive right hand rule for solenoids

Answer 26

fingers are now the current Thumb is now the magnetic fields