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Physics > Electromagnetism > Flashcards

Electromagnetism Flashcards

all about electrical fields ,magnets ,generators ad power

1
Q

Number one rule of charges

A

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

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2
Q

what do objects with charge produce ?

A

an electric field

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3
Q

Electric field lines show what ?

A
  • 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
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4
Q

The interaction of Negative and positive charges electric fields

A

Always away from the positive
torwards the negative

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4
Q

Force on charges in an Electric field

A
  • positive charges feel a force in the direction of the field lines
  • Negative charges feel a force opposite the direction of the field lines
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5
Q

The Definition Of ELECTRIC FIELD STRENGTH

A

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

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6
Q

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

A
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7
Q

For calculations of elecrtic field for two diffent charges remember

A

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

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8
Q

Producing a uniform electric Field

A

The electric field between two charged parallel plates is found by

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9
Q

Electric Field

A

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)

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9
Q

Electrical Potential Difference(Voltage) formula

A
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10
Q

Final Kinetic energy for Particle in electromagnetism

A

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

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11
Q

Potential difference in an electrical field

A

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

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11
Q

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

A

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

1.6x10^-19 J=1eV

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12
Q

Commit this to memory

A
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12
Q

Remember the curves lines on the edge of the plates!

A
13
Q

Work in an electric field

A

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.

14
Q

the more charge the object has …

A

The more work we had to do to change its location

15
Q

Electric work

A

W=Vq =qEd

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

15
Q

Earths Magnetic field

A
If It's In the Northern Hemisphere the field Is DECLINED If in The Southern Hemisphere the filed IS INCLINED
15
Q

LIST three changes that can make an electromagnet More Effective

A
16
Q

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

A

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

17
Q

ELECTROMAGNETIC FIELDS IN A LONG WIRE,LOOP AND SOLENOID

A

Important

18
Q

Parts of A Motor

A

Important memorise this

19
Q

why does an electric motor rotate

A

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

20
Q

Calculations

A
20
Q

Faraday’s Law

A

a changing Magnetic flux through a loop will induce an EMF

21
Q

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

A
1.Calculate the flux(wbs) 2.the use the flux to calculate the induced emf through the formula in the pictures(V)
22
Q

lenz’s Law

A

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)

23
Q

FARADAY’S LAW CONTINUED

A
ALL OF THE QUANTITIES ARE PERPENDICULAR TO EACH OTHER
23
Q

please note

A

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

24
Q

GUIDE TO ANSWERING FARADAY’S LAW QUESTIONS

A
25
Q

GUIDE TO ANSWERING FARADAY’S LAW QUESTIONS 2

A
26
Q

alternitive right hand rule for solenoids

A
fingers are now the current Thumb is now the magnetic fields

Physics (12 decks)

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