Midterm Tufree Physics II

7/25/2019 Midterm Tufree Physics II

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GENERAL PHYSICS II

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1 Electro StaticsCoulomb

s law

rR

QkQF

2

21

1. 4 4 4

A.(3),(1),(2),(4) B.(4),(2),(1),(3)

C.(2),(3),(4),(1) D.(1),(4),(3),(2)

E.(3),(4),(1),(2)

3. 4 2

A.(a),(b),(v),(d) B.(a),(b),(c)

C.(a),(b) D.(a)

E.(b),(c),(d)


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GENERAL PHYSICS II


2 Charge is Quantized

Q (C)N e

= -1.610-19C

3 The Electric Field

rR

kQE

2

Electric Dipole

Q = Ne


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GENERAL PHYSICS II


4 Electric Field Continuous Charge

Distributionr

r

dqkE

2

Volume charge density:when a charge is distributed evenly throughouta volume

= Q/ V

Surface charge density:when a charge is distributed evenly over asurface area

= Q/A

Linear charge density:when a charge is distributed along a line

= Q/

EX. Line Charge


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GENERAL PHYSICS II


EX Charged Disk

5 Gausss Law

Electric fluxis the product of the magnitude of the electric field and the

surface area,A, perpendicular to the field

AdE

Gauss lawrelates the net flux of an electric field through a closedsurface (a Gaussian surface) to the net charge q

encthat is enclosed by

that surface.


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GENERAL PHYSICS II


0

encqAdE

EX Applying Gausss Law

Cylindrical Symmetry

Planar Symmetry

Spherically Symmetric


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GENERAL PHYSICS II


4.

A. B.

C. D.

E.

6. 3

= 2.00 R= 100 cm

7. 1.50 m

= (3.00 4.00) 6.00 7.00

6 Electric Potentialand Potential EnergyConsider two charged particles. The potential energy of the system is

12

21

R

QkQU

The electric potential is

R

kQV


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GENERAL PHYSICS II


1.

2.

7. Equipotential Surface A.B.C.D.E.


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GENERAL PHYSICS II


Electric Field from Potential

In general, the electric potential is a function of all three dimensions

Given V(x,y,z) you can findEx

,Ey

andEz

as partial derivatives

V(x,y,z) =

1. = 3 2

E. A D ................................................. N/C

2. r = 3 2

A.2.51 10NB. 5.20 10NC. 7.53 10ND. 1.00 10NE. A D ................................................. N

3. + r = 3 2 r = 3 2 A.-1.85 10JB.1.85 10JC.-4.19 10JD.8.39 10JE. A D ................................................. J

x y z

V V VE E E

x y z


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GENERAL PHYSICS II


4. r = 3 2 1A.628.3 CNm /2 B.-628.3 CNm /2 C.377.0 CNm /2 D.-377.0 CNm /2 E. A D ................................................. CNm /2

7

Capacitance

C (Farad;F)Q

V

(Combination of Capacitors)

1. (Series Combination) Q (Q1= Q2= Q3= Q) V

Ceq

V

QC

CVQ

...1111

321

CCCCeq


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GENERAL PHYSICS II


2. (Parallel Combination) V (V1=V2= V3= V) Q

Ceq

1. C1=1.16 F C

2=3.22 F V=96.9 v

a c b d S1

S2 C

1,C

2 e f

1. C1= C

5= 8.4 C

2= C

3=C

4= 4.2 V

ab= 220

...321 CCCCeq


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GENERAL PHYSICS II


A. a b 2.5

B. C1 5.5 x 10-4

C. V5= 66V voltage C5

D. A,B,C

E. A,B,C

Capacitors with Dielectrics

A dielectricis a nonconducting material that, when placed between the plates ofa capacitor, increases the capacitance

Dielectrics include rubber, plastic, and waxed paper

0CC The capacitance is multiplied by the factor when the dielectric completely fillsthe region between the plates.

W (J)V (Volt)

QVW2

1

2

2

1CVW

C

QW

2

2

1


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GENERAL PHYSICS II


6. a,b =

Electric Circuits


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GENERAL PHYSICS II


() (Q)

(C/s) (A)Q (C)t (s)

1 (Resistivity)

(R)

(Resistivity) (m)

(m)A (m2)

4. 6 3

A.54

B.55

C.56

D.57

E.58

tQI

AR


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GENERAL PHYSICS II


2 Kirchhoffs Rules1 Junction rule

321 III

2 Loop rule

A B(VAB= VA VB)

1. 2. A B 3. A B

I = I

Loop Loop

IRE


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GENERAL PHYSICS II


4.

A. Vad

6.58 V

B. Vad

4.58 V

C. 4.00 V 3.983 V

D. 4.00 V 4.00 VE.

3. A

RE

RD

RC

RB

RA

12

10.

9

8.

7.


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GENERAL PHYSICS II


5. P 100 V Q

A. -10V

B.+10VC.-20V

D.+20V

E.+30V

3 RC Circuits:

Charging

The charge on the capacitor varies with time

q(t)= C (1 e-t/RC

) =Q(1 e-t/RC

)

The current can be found

RCteRdt

dqti /)(

is the time constant = RC

Discharging

q(t)= Qe-t/RC

2. RC t= 0 s 100 V,

1.06 V 10 s t=17s A.2.2 , 44

B.3.3 , 66

C.4.4 , 88D.5.5 ,100


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GENERAL PHYSICS II


E.6.6 ,110

Magnetic Fields

1Magnetic Force

F

(N)

q (C)v (m/s)B

(T)

v B

2. 50 cm 2.0 N/C

A. 5.5610-11 B. 5.5610-7

C. 1.3910-11

E. 2.2210-11

BvqF

sinBvqF


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GENERAL PHYSICS II


5. 75.0 cm 0.860 T x

a b c d e f 6.58 A f N

A.

-4.24 B.-4.24 C. 4.24 D. 4.24 E. 4.24 -4.24

B.

(T)

(Helical Path)

qB

mvR

qB

mT

2


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GENERAL PHYSICS II


1.

2.

3.

14. 22.5 B=455 T 65.5

A.75.6 ,1.2

B.76.6 ,1.2

C.77.6 ,2.2

D.78.6 ,3.2

E.79.9 ,3.2

7.K d

m e

qB

mvR

sin

qB

mT

2

S

qB

mv

2

cos


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GENERAL PHYSICS II


(Magnetic Force Acting on a Current Carrying Conductor)

F

(N)I (A)

(m)

B

(T)

B

BIF

sinBIF


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GENERAL PHYSICS II


7. AB I CD AB

C D CD

I AB CD CD

h

AB

2

E (Volt)L (m)v (m/s) v B

E Bv

E = LvBsin


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GENERAL PHYSICS II


10.

11. = 262 = 12.7 = 13 477

A.1.33A

B.1.44A

C.1.55A

D.1.66A

E.1.78A

3 Amperes Law

enciSdB 0


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GENERAL PHYSICS II


Solenoids and Toroids

r

iNB

2

0

inB0

4 Faradays Law of Induction

dt

dN B

AdBB

Induced Electric Fields

dt

dSdE B

12.


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GENERAL PHYSICS II


13. = 12, = 16

emf = 3A.300 B.400

C.500

D.600

E.660

9.

b


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GENERAL PHYSICS II

12. AB di/dt

a)

b) emf

c) emf

a=12.0 cm b=36.0 cm L=24.0 cm di/dt=9.60 A/s

10. 4.00 cm 0.0280A 1.00 cm

A.7.5 x 10-7T B. 6.5 x 10-7T C.5.5 x 10-7T

D. 4.5 x 10-7T E.3.5 x 10-7T

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Midterm Tufree Physics II