Hostos Community College, Natural Science Department, Calculus Base Physics II

Final Exam, 2013 Spring

- A spherical surface (radius
= 1m) is uniformly charged (electric charge**R**= 1 C). What the surface-tension**Q**does this electric charge produce?**T** - An isolated system of three contacted solid bodies ( masses:
**m**_{1},**m**_{2},**m**_{3}, specific heat capacities:**c**_{1},**c**_{2},**c**_{3}) have equilibrium temperature**T**_{f}. If initial temperatures of two bodies are known (**T**_{1},**T**_{2}), what was the initial temperature**T**_{3}of third body? - Three separately located capacitors (capacities:
**C**_{1},**C**_{2},**C**_{3}) with the electric charges:**Q**_{1},**Q**_{2},**Q**_{3}initially are not connected by conductors. Then capacitors have been connected by conductors into the open parallel circuit. What is the change of the total potential electric energy between the initial and final configuration. - A spherical object (
<**r**) charged with the uniform electric charge density:**R**= 3**ρ**/(4π**Q****R**^{3}).

a) Find the electric field=**E**(**E**), 0 ≤ r ≤ ∞ ;**r**

b) Find the electric potential=**V**(**V**), 0 ≤ r ≤ ∞ .**r** - A spherical object (
<**r**) charged with the electric charge density:**R**=**ρ**(**ρ**) =**r**/(2**Q****rR**^{2}).

a) Find the electric field=**E**(**E**), 0 ≤ r ≤ ∞ ;**r**

b) Find the electric potential=**V**(**V**), 0 ≤ r ≤ ∞ .**r** - Four identical electric charges are located in the vertexes of a regular tetrahedron (triangular pyramid). Total electric potential energy of these electric charges is 6J. What will be the total potential energy of the same configuration if only one electric charge will change the sign.
- If three parallel resistors have the relation of their resistances (
**R**_{1}/**R**_{2}/**R**_{3}) as (1:2:3). What is the relation of currents (**I**_{1}:**I**_{2}:**I**_{3}) on these parallel resistors? - If three series resistors have the relation of their resistances (
**R**_{1}/**R**_{2}/**R**_{3}) as (1:2:3). What is the relation of voltages (**V**_{1}:**V**_{2}:**V**_{3}) on these series resistors? - In how many time will change the apparent weight of 100 kg man on the surface of the Earth, if each kilogram of the Earth mass will be charged by electric positive elementary charge, and each kilogram of the man mass will be charge by negative elementary charge?
- If loudness of the first sound source greater than loudness of the second sound source on the 30 Db. What is the ratio of the sound intensities
**I**_{1}/**I**_{2}? - Draw the rays diagram and calculate the position of the image if the object's location is 9 cm in front of converging lens with focal length 3cm.
- A plane sinusoidal electromagnetic wave in some transparent media is described for the electric field by equation:
=**E**(**E**,**x**)=**t**sin(**Aj**-**Bx**), where**Ct**is time,**t**is**x**-coordinate,**x**is unite vector to**j**direction.**y**

a) What is the direction of wave propagation?

b) What is the wave speed?

c) What is the refraction index of the transparent media?

d) What is the frequency?

e) What is the wave length? - Unpolarized light passes through 5 parallel ideal polarizing filters. The angles between polarizing axis of two consecutive filters are identical and equal to 30 degrees. What is the ratio of the initial intensity to the final intensity of the light?
- Straight, infinitely long conductor with the current
produces the magnetic field**I**on the distance**B**from the conductor. What are possible magnetic fields on the central axis of three parallel infinite conductors with the same currents if the distance between any two conductors equals to**R**.**R**