Lab 10: Dipole Moments and Flux

  There is a rod with positive charge. Another rod with negative charge is on top of the positive rod. The direction of the electric field is going upward. A negative charge particle put into the electric field. As you see, it is moving downward.

  The direction of the electric dipole is from negative particle to positive particle. When an electric dipole in the electric field, the force on the two particles is opposite.

  Then we used equation we learned in 4A Torque=Fr to found the torque in electric dipole. We found electric moment P=2qa and torque in electric dipole=PE.

  We found out work is the change of potential energy.

  This is prediction  3-D diagram for electric dipole. In second image, we did a program to express the  electric dipole by using Vpthon.

  Then we found out the direction of a electric field is from positive charge to negative charge.

  This is the unit we found for flux.

  For a cube, flux is zero on side 3 and 4. But it exists on side 1 and 2.

  Today, we started talking about electric dipole and flux. Direction of a electric dipole is always from negative electron to positive electron. Coding a program for electric dipole was a big trouble for us. We spend lots of time to work for it. For the flux, we found out the unit for flux is Nm^2/C and flux=Ecosθ*A.

Day 9: Electric Field

  Profess Mason wanted us to use the gravity definition to define electric definition.

  We found out the equation E=k*q_2/r^2 by combined the equations F=k*q_1*q_2/r^2 and E=F/q.

  This is a 3-D diagram for a proton. As you see, the direction of the electric field is going outward.

  There are four steps to found E.

  This is our prediction for the electric vector and direction. The second image is the correct electric vector and direction we did by using Vpthon, which is match our prediction.

  These are the images of the program we did by using Vpthon.

  This is an example problem we did in class. There are two particles on the x-axis. One is positive and the other is negative. We need to use the equation E=k*q/r^2 to found the total E of a special position.

    Then another positive particle added on the y-axis, we still need to found the total E. 

  This is another example problem. But we could use Excel to found the total E which was an easy way.

  We put an electron on top of the center rod. We still need to found the total E. But first, we need solve Ex and Ey. Then we could solve for the total E which is 110210 N/C. The second image shows a different way to found total E. The answer we got is 60000 N/C which was very close to the answer we got in the Excel 59715 N/C in the first image.

  Today, we started with the definition of the electric field. Then we figure out a new equation E=k*q_2/r^2 by combined the equations F=k*q_1*q_2/r^2 and E=F/q. After we found out this equation, we did a very interesting program by using Vpthon. After the programming, we started doing some example problems to solve for total E by using Excel.

Lab 8: Electric Charge and Force

  Professor Mason hold a balloon and rubbed to his hair. Then he hold the balloon and the balloon sticked on the wall, which match our prediction.

  Then Professor Mason rubbed this balloon to a silk. Some result, it sticked on the wall. This experiment tells this balloon will produce charge after rubbing, and these charges will make the balloon sticky.

  This is the definition of charge for 7 year old.

  Then we started Interactions of Scotch Tape Strips experiment. We peeled two tapes off the table and bring them to each other. We found out they pushed each other away. In the second video, still 2 strip of tapes. We put a tape "T" on top of the tape "B". Then we peeled these tapes, we found "T" tapes were against each other and "T" and "B" tape were stick together.

 

  After the Interaction of Scotch Tape Strips experiment, we did an example problem form the lab manual.

  This is our prediction graph for F and r.

  Then we did a Electrostatic Force lab on the Logger Pro. And this is the graph we got on the Logger Pro.

  We believe a positive charge and a negative charge will attract each other.

  Then we did a problem by using the equation F=kq1q2/r^2.

  There is another problem we did in class by using the equation F=kq1q2/r^2. But this time, we need to found the force on the x-axis and y-axis.

  As you see, all these papers are floating on the equipment. Then we put a propeller on top of the equipment, and this propeller started rotating.

In conclusion, we started a new chapter today. We started talking about electric instead of heat. At beginning of the class, Professor Mason did a very interesting experiment, he rubbed a balloon by his hair to make this balloon produce charge so it can stick on the wall. Then we did the interaction of two tapes experiment. If we peel two tapes from the table, they will against each other. Last, the equipment could produce electric so it can make this pie fan spin.

Vpthon

Lab 7: Entropy and Cycles

  When we put ice on the top of the equipment and under with hot water, the fan started rotating. In the other hand, if we put hot water on the top and under with ice water, the fan rotated opposite direction.

  We know ice is 0°C and hot water is 80°C, so we could found out efficiency.

  Then we started doing a example problem to found COP (coefficient of performance) and Q_h.

  We learned how to found effectiveness and did an example problem.

  Because we know the reversile process is constant, so we could found the final temperature.

  Then we found out the efficiency of the Carnot cycle and the efficiency of the reversile process.

   There is another example problem for us to solve Q_c and Q_h. After we known Q_c and Q_h, we need to found how long could 4.2kg of water freeze to ice.

  Last, we did a bubble demo. Bubbles will fell down if the bubbles make by air. However, bubbles will go up if the bubbles make by gas.

  Today, we did two experiments and many example problems. For the Stirling cycle experiment, the fan will rotate if we put ice on top and hot water at bottom. Also, it will rotate opposite direction if we put hot water on top and ice at bottom. We could use T_h/(T_h-T_c) to find COP. For the bubble experiment, we understood that bubble will fells down if it makes by air and goes up if it makes by gas.