Quiz#1                                                                 Solution                                                                       

Sunday, September 18, 2005                                                                                                          Sec:7

 

A sinusoidal transverse wave travels along a string. The time for a particle on the string to move from maximum displacement to zero displacement is 0.170 seconds. What is the frequency of the source?

(a)        23.3 Hz

(b)        1.47 Hz

(c)        8.96 Hz

(d)        2.94 Hz

(e)        5.88 Hz

 

Solution:               Displacement

                                                                                                     .

            T = 4(0.17)

               = 0.68 s

                 

           

                = 1.47 Hz

            The solution is (b).

 

Quiz#1                                                                 Solution                                                                       

Tuesday, September 21, 2005                                                                                                         Sec:8

 

A string 180 cm long has a fundamental frequency of vibration of 300 Hz. What length of the same string, under the same tension, will have a fundamental frequency of 200 Hz?

(a)        900 cm.

(b)        270 cm.

(c)        120 cm.

(d)        147 cm.

(e)        220 cm.

 

 

 

 

Solution:

            For L=180 cm

           

           

                      

           

            For the new length:

 

           

            The speed is the same because tension and linear mass density are the same:

           

            L= 270 cm

 

The solution is (b).

 

 

Quiz#1                                                                 Solution                                                                       

Sunday, September 18, 2005                                                                                                          Sec:9

 

Ocean waves, with a wavelength of 12 m, are coming in at a rate of 20 crests per minute. What is their speed?

(a)        8.0 m/s

(b)        4.0 m/s

(c)        24  m/s

(d)        30  m/s

(e)        16  m/s

 

Solution:

            Frequency =

           

                = 4 m/s

 

 

The solution is(b).

 

 

 

 

 

 

Quiz#2                                                                 Solution                                                                       

Sunday, September 25, 2005                                                                                                          Sec:7

 

When a certain string is clamped at both ends, the lowest four resonant frequencies are 50, 100, 150 and 200 Hz. When the string is also clamped at its midpoint ( without changing the tension), then the lowest four resonant frequencies are

(a)        50, 100, 150  and 200 Hz.

(b)        35, 50 , 75   and 100 Hz.

(c)        75, 150, 225  and 300 Hz.

(d)        50, 150, 250  and 300 Hz.

(e)        100, 200, 300 and 400 Hz.

 

Solution:

                                                            L

 

                                                        L/2

            For length =L 

                                                                    here  

            For length =

                           =  

                                             =  n(100)

            The Solution is (e)

 

 

 

 

 

 

Quiz#2                                                                 Solution                                                                       

Tuesday, September 27, 2005                                    Sec:8 A sound wave of 50.0 cm wavelength enters the tube shown in figure(1) at the source end. What must be the smallest radius(r) (other than zero) such that a maximum sound will be heard at the detector end?

(a)        15.9 cm.

(b)        21.3 cm.

(c)        33.0 cm.

(d)        17.5 cm.

(e)   43.8 cm.

 

 

 

Solution :

                      

 

                     The solution is (e).

 

 

Quiz#2                                                                 Solution                                                                       

Sunday, September 25, 2005                                                                                                          Sec:9

 

 

A 40 cm string of linear mass density 8.0 g/m is fixed at both ends. The string is driven by a variable frequency audio oscillator ranged from 300 Hz to 800 Hz. It was found that the string is set in oscillation only at the frequencies 440 Hz and 660 Hz. What is the tension in the string?

(a)        125 N.

(b)        496 N.

(c)        500 N.

(d)        322 N.

(e)        248 N.

 

Solution:

           

           

                    1              

= 660 – 440

           

= 220 Hz

           

           

           

           

           

           

   = 248 Hz

 

 

            The solution is  (e)

 

 

fi Quiz#3                                                              Solution                                                                       

Sunday, October 2, 2005                                                                                                                Sec:7

nal-032-Q02                                                                                                                                                                                        18-05

Question 1                                                                                                                                                                                0.33-72%

A point source emits 30 W of sound. A small microphone has an area of 0.75 cm**2 is placed 10 m from the point source. What power does the microphone receive?

(a)        30  micro-W.

(b)        0.1 micro-W.

(c)        9.3 micro-W.

(d)        1.8 micro-W.

(e)        3.6 micro-W.

            Solution:

           

            The intensity for a point is given by

                                   

                                   

                                   

                                                           

                                   

            The solution is (d).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Quiz#3                                                                 Solution                                                                       

Tuesday, October 5, 2005                                                                                                               Sec:8

A pipe is closed at one end and open at the other, and has a length of 0.500 m. The pipe is filled with air. What is the resonant frequency corresponding to the mode shown in figure 5? Use 344 m/s as the speed of sound in air.

(a)        172 Hz

(b)        429 Hz

(c)        344 Hz

(d)        515 Hz

(e)        860 Hz

 

 

            Solution:

           

For a pipe closed from one end, the harmonic number is given by two number of quarter, there we have 5 quarters waves, thus n=5

                        

                        

           

The solution is (e).

 

 

Quiz#3                                                                 Solution                                                                       

Sunday, October 2, 2005                                                                                                                Sec:9

Question 2                                                                                                                                                                                0.19-59%

In figure 1, two speakers, A and B, are driven by the same oscillator at a frequency of 170 Hz and face each other at a distance of 2.0 m. What is the number of minima along the line joining the two sources? [Consider only the nodes between the two sources.] [Take the speed of sound in air = 340 m/s]

(a)        2

(b)        4

(c)        1

(d)        5

(e)        zero

 

           

Solution:

           

                                         0.5m

 

                                   

 

                                                                        At the middle we have antinode.

 

            Number of nodes where you have minimum intensity is 2.

 

The solution is(a).

 

 

 

fQuiz#4                                                                Solution                                                                       

Sunday, October 9, 2005                                                                                                               Sec: 7

 

The wall of a home is 0.2m thick, 0.2m high, 10 m wide and has a thermal conductivity of 0.4 watt/m/K. If the inside temperature is 15 degrees Celsius and the outside temperature is -5.0 degrees Celsius, how much energy is lost in 12 hours?

(a)      4.5*10**6 J.

(b)      4.5*10**5 J.

(c)      4.5*10**6 J.

(d)      2.7*10**7 J.

(e)      3.4*10**7 J. 

 

Solution:

 

     

     

     

The solution is(e).

 

 

 

 

 

 

fQuiz#4                                                                Solution                                                                       

Sunday, October 11, 2005                                                                                                             Sec: 8

 

A cylinder with a frictionless piston contains 0.2 Kg of water at 100 degrees Celsius. What is the change in internal energy of water when it is converted to steam at 100 degrees Celsius at constant pressure of 1 atm.[Density of steam =0.6Kg/m**3, water =10**3Kg/m**3]

Heat of vaporization for water is 2256 kJ/kg. 1atm = 1.01 X 10**5 Pa.

 

(a)          418kJ

(b)          452kJ

(c)          226 kJ

(d)          113 kJ

(e)          333 kJ

 

 

 

 

Solution:

           

           

           

 

            The solution is(a).

 

 

fQuiz#4                                                                Solution                                                                       

Sunday, October 9, 2005                                                                                                               Sec: 9

 

One kilogram of water id initially at a temperature of 30.0 degrees-C. How much ice, initially at a temperature of zero degrees-C, must be added to the water to make a mixture whose equilibrium temperature is 10.0 degrees-C?[ The specific heat of water is 4190J/kg.K and the heat of fusion is 333kJ/kg.]

(a)    252g

(b)    224g

(c)    452g

(d)    200g

(e)    476g

           

 

 

 

 

 

Solution:

 

                                                                       

 

 

 

           

           

 

 

            The solution is(b).

Quiz#5                                                                 Solution                                                                       

Sunday, October 23, 2005                                                                                                              Sec:7

 

A charge of +3.2*10**(-6) C is placed at the origin. A second charge (q2) is placed at x =3.0m. If a charge of 1.0*10**(-6) C experiences no force if placed at x=4.0 m , then q2 is :

(a)        +0.2*10**(-6) C.

(b)        -3.3*10**(-6) C.

(c)        -0.2*10**(-6) C.

(d)        +0.2*10**(-6) C.

(e)        -2.1*10**(-6) C.

 

Solution:

 

            q1=+3.2*10**-6                                                                 q2              F32    q3=1.0*10**-6

                                                                                                                                                          F31

                                                3.0 m                                                               r32=1m

                                                                        r31=4.0 m

 

               The charge of q2 should be negative, since the force on q3 due to q2 should point to

the left.

                                                 

                                               

 

 

 

 

 

                                               

 

The solution is (c).

 

 

 

 

 

 

 

 

 

 

 

 

 

Quiz#5                                                                 Solution                                                                       

Sunday, October 25, 2005                                                                                                              Sec:8

 

In figure 3, Q = 60 micro-C, a = 3.0 m, and b = 4.0 m. Calculate the total electric force on q. [I and j are the unit vectors in the positive directions of x-axis and y-axis, respectively].

           

                                             Y

                                           Q

 

                                                             B

 

                                                                                   

                                                                                   q      X

           

 

 

                                             Q

 

(a)    1.12j(N)

(b)   -0.34 I (N)

(c)    -0.69 i(N)

(d)   0.34 I (N)

(e)    0.69 I (N)

                                                                                  

 

Solution:

 

                                               

                                             Y

                                           Q

 

                                      a                    B

 

 

                                                                                   q      X

           

                                       a

 

                                             Q

 

 

                        Along y-axis     Fy = 0

                        Along X-axis        Since

                                                           

Quiz#5                                                                 Solution                                                                       

Sunday, October 23, 2005                                                                                                              Sec:9

 

Charges q1 and q2 are on the x-axis. q1 is at x = a and q2 is at x = 2a. The net force on a third charge at the origin is zero. Which of the following is TRUE?

 

(a)      q2 = -4*q1

(b)      q2 = 2*q1

(c)      q2 = 4*q1

(d)      q2 = -q1

(e)      q2 = -2*q1

 

 

Solution:

 

                                       q3                             q1                                   q2

 

                                                            a                                                                                                                                                                                                                                                                                                                                     2a

 

 

 

                                   

 

            The sign of q2 should be opposite of that of q1 since their forces on q3 should point in opposite directions.

 

The Solution is(c)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Quiz#6                                                                 Solution                                                                       

Sunday, November 13, 2005                                                                                                           Sec:7

 

 

 

 

 

 

                       

 

                                    Vf       

 

 

 

 

 

 

                                                                        Vi = 50

                       

                       

                       

 

 

Quiz#6                                                                 Solution                                                                       

Sunday, November 15, 2005                                                                                                           Sec:8

 

 

                        Total flux = 0

                                                            Flux through Ф1 cone

                       

           

 

 

                                                              Ф2 flux through the base

 

 

Quiz#6                                                                 Solution                                                                       

Sunday, November 13, 2005                                                                                                           Sec:9

 

A proton is shot out along the +x-axis from the origin with a speed of 1.0*10**6 m/s. In this region a uniform electric field of 2500 N/C exits in the negative x-direction. Find the distance traveled by the proton before it momentarily comes to rest.

 

(a)    8.9 m

(b)   1.0 m

(c)    4.2 m

(d)   2.1 m

(e)    2.9 m

 

E = 2500 N/C

 

 


p          Vi = 1.0*10**6 m/s

           

 

 

           Charge of the proton =  

                      

                                               

                                                          

         Mass of the proton

= 1.7*10**-27

                                                        

 

 

 

Quiz#7                                                                 Solution                                                                       

Sunday, Nov.20, 2005                                                                                                                    Sec:7

 

For the two infinite dielectric sheets, see figure(5), find the magnitude of the electric field at a point P. consider that each sheet has a positive surface charge density of 10**2 C/m**2

 

 

                                               

                                                            0.5 m  

 

 

                                                                                                1.0 m        P    

 

 

 

 

 

 

 

(a)   2.2*10**13 N/C

(b)   0.5*10**13 N/C

(c)   1.1*10**13 N/C

(d)   Zero

(e)   1.7*10**13 N/C

 

 

 

Solution:

                                        but

                          

 

 

            The solution is (c).

 

Quiz#7                                                                 Solution                                                                       

Tuesday, Nov 22, 2005                                                                                                                   Sec:8

 

A nonconducting shell has a uniform negative charge of magnitude 5.0*10**(-5) C. Its inner and outer radii are 5.0 cm and 6.0 cm, respectively. The electric field at r = 3.0 cm, from the center, is:

(a)    4.5*10**9 N/C, inward.

(b)   1.5*10**9 N/C, outward.

(c)    4.5*10**9 N/C, outward.

(d)   1.5*10**9 N/C, inward.

(e)    Zero.

 

 

 

 

 

 

Solution:                                                                                               Total charge 5*10**5 C

                    6cm                     

                                                     3 cm           

                                                                   5cm

 

 

 

 

 

                                                            E at 3 = zero.

 

The solution is (e).

 

 

Quiz#7                                                                 Solution                                                                       

Sunday, Nov. 20, 2005                                                                                                                   Sec:9

 

Figure 4 shows cross-section through two large, parallel non-conducting sheets with identical distributions of negative charge. The surface charge density for each sheet is 7.00*10**(-15) C/m**2. What is the electric field at point A?

                                                                        A

 

 

 

 

 

(a)        7.91*10**(-4) N/C upward.

(b)        3.96*10**(-4) N/C downward.

(c)        3.96*10**(-4) N/C upward.

(d)        7.91*10**(-4) N/C downward.

(e)        0

 

Solution:

                                   

 

                                                   E1          E2

 

 

Downward

 

The solution is(d).                                            

                                               

 

 

 

 

 

 

 

 

Quiz#8                                                                 Solution                                                                       

Sunday, Nov. 27, 2005                                                                                                                   Sec:7

nal-032-Q02                                                                                                                                                                                        18-05

Question 1                                                                                                                                                                                0.33-72%

Two large, parallel, conducting plates are 20 cm apart and have charges of equal magnitude but opposite signs on their facing surfaces. An electron, placed anywhere between the two plates experience an electrostatic force of 1.6*10**(-15)N. Find the magnitude of the potential difference between the two plates.

(a)        30 kV.

(b)        50 kV.

(c)        2 kV.

(d)        10 kV.

(e)        4 kV.

            Solution:

                       

 

                                                                        F

                                                                  e

 

 

 

                                                                            20 cm                                                                                                                                     plate                  plate

 

                                   

                                    Uniform electric field:

                                   

                                    =2 kV

 

            The solution is (c).

 

Quiz#8                                                                 Solution                                                                       

Tuesday, Nov. 29, 2005                                                                                                                  Sec:8

Question 2                                                                                                                                                                                0.54-65%

Over a certain region of space, the electric potential is give by: V(x,y) = x**2+y**2+2*x*y. find the angle that the electric field vector makes with Z-axis at point(1.0,2.0,0.0).

 

(a)        75 degrees

(b)        45 degrees

(c)        90 degrees

(d)        0 degrees

(e)        60 degrees

            Solution:

                       

 

                        Electric field is in x-y plane:

           

                       

 

Quiz#8                                                                 Solution                                                                       

Sunday, Nov 27, 2005                                                                                                                    Sec:9

Question 3                                                                                                                                                                                0.19-59%

An infinite nonconducting sheet has a surface charge density 0.10*10**(-6) C/m**2 on one side. How far apart are equipotential surfaces whose potentials differ by 90 V.

 

(a)        2.0 cm.

(b)        1.6 cm.

(c)        0.88 cm.

(d)        1.8 cm.

(e)        2.5 cm.

 

            Solution:

 

           

            Uniform electric field:

           

 

 

            The solution is (c).

                                            

 

 

 

 

 

 

 

Quiz#9                                                                 Solution                                                                       

Sunday, Dec 4, 2005                                                                                                                       Sec:7

Question 3                                                                                                                                                                                0.19-59%

If Vab is equal to 50 V, find the charge sloted  and the potential difference across the 25 nicro-F capacitor shown in Figure 5.

 

(a)        600 micro-C and 10V.

(b)        250 micro-C and 40V.

(c)        300 micro-C and 20V.

(d)        600 micro-C and 20V.

(e)        250 micro-C and 10V.

 

            Solution:

                                            

                                       C12    60 μF         

                                           C3     15 μF

 

 

                                                 q = 600 μC

 

                                    C123                 12 μF

 

 

                     Charges on C12 = Charges on C123

                                                =  600 μC

                    

                     Voltages on C12 =

 

                     Charges on the 25 μF is (10V)(25 μF) = 250 μC

                    

                        The solution is (e).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Quiz#9                                                                 Solution                                                                       

Sunday, Dec 6, 2005                                                                                                                       Sec:8

Question 3                                                                                                                                                                                0.19-59%

A certain air filled parallel-plate capacitor is connected across a 20 V battery. When the battery is disconnected and a dielectric slab is inserted into and fills the region between the plates, the voltage across the plates drops by 12 V. What is the dielectric connect of the slab?

 

(a)        2.5

(b)        1.7

(c)        0.4

(d)        2.1

(e)        0.6

 

            Solution:

                                                            V = 20 v                     

                       

 

                                                         Air          qi

 

 

                                                                        V = 12 v

 

                                                                          qf

 

 

                       

                                                            Since between is

                                                            Not connected                         

                       

                       

 

 

 

 

                        The solution is(b).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Quiz#9                                                                 Solution                                                                       

Sunday, Dec 4, 2005                                                                                                                       Sec:9

Question 3                                                                                                                                                                                0.19-59%

A parallel plate capacitor has a plate area of 0.2m**2 and a plate separation of 0.1 mm. the charge on each plate is 4.0 microCoulombs. What is the electric field between the plates?

 

(a)        1.0*10**6 V/m

(b)        4.0*10**12 V/m

(c)        2.3*10**6 V/m

(d)        4.0*10**2 V/m

(e)        zero

 

            Solution:

 

                       

 

                       

                                               

                        The solution is(c).