Electricity & Magnetism 1 Flashcards

1
Q

Conductor

A

Material that permits flow of charge

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2
Q

Charging by induction

A

Negatively charged rod brought near uncharged metal ball

Causes one side of ball + (closest to rod) and other -
If connect RHS with conducting wire to ground, charge will flow from ball to Earth
Disconnecting leaves + ball

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3
Q

Coulomb’s law

A

F=k|q1q2|/r^2

k=1/4piE0 = 9x10^9

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4
Q

Electric field

A

Force F0 that charge q0 feels at point, divided by charge
E=F0/q0

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5
Q

+ q0

A

Same direction for force and E0

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6
Q

-q0

A

Opposite directions for F0 and E0

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7
Q

Radial vector in electric field equation

A

E=k q/r^2 r^

r^ is like i^j^k^

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8
Q

Magnitude of radial vector

A

|r^|=1

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9
Q

Resultant field

A

Add components

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10
Q

Field lines

A

Away +
Towards -

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11
Q

Work done

A

W a—>b =Fd= q0Ed

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12
Q

Potential energy

A

U=k qq0/r

Or = k sum of qiqj/rij

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13
Q

Electric potential

A

V=U/q0

Potential= potential energy/charge

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14
Q

Inside sphere

A

No electric field

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15
Q

Graph of E against r for sphere

A

Start along x axis for inside sphere
Sloping down y axis after

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16
Q

Potential inside sphere

A

Same at every point inside

17
Q

Graph of v against r

A

Constant whilst inside Spencer’s then slope down y axis once outside

18
Q

Equipotential surface

A

Potential same at every point

19
Q

Equipotential lines

A

Perpendicular to field lines (meet at right angles)

Stronger E field = closer together Equipotential

20
Q

Potential gradient

A

E=- pot grad

21
Q

If E is radial

A

Er=dv/dr

Need to calculate x,y and a components of E field

22
Q

Moving charge produces

A

Magnetic field

23
Q

Second moving charge

A

Experiences magnetic force

24
Q

Unit of magnetic fields B

25
Particle at rest
No magnetic field
26
Relation between F, B and v
F perpendicular to B and v (rh rule)
27
Cross product for F
qVxB VxB found using 3x3 matrix discriminant
28
If both E and B
F=q(E+VxB)
29
Magnetic field lines
Parallel, straight, evenly spaced= uniform magnetic field
30
Into page
x
31
Out of page
o
32
Unit of magnetic flux
Webber (Wb)
33
Torque
t=IBAsin theta
34
Magnetic flux
I=BAcos theta
35
Ampere’s law
Integral B.dl = u0l enclosed
36
Comparing charged particles in mag filed with circular motion
F=|q|vB=mv^2/r
37
Pitch
Distance travelled along x axis in 1 rotation =2pi/w
38
Magnetic moment
u=IA (A=area) Anything that experiences a magnetic torque is often known as a magnetic dipole
39
Maximum torque that can be obtained with same total length of wire carrying same current in same mag field
Max will occur when A is max Max area when area is a circle Calculate circumference then radius and then plug in to equation for torque