Exercise 3: Laws of voltage and current (12 pts)
The adjacent diagram is a portion of an electric circuit:
Given I=10 A, L =5 A, L = 3 A, la = 1 A, and is = 3A.
Li, L2, ..., and Ls are lamps.
The points A and B are connected to a battery.
1
itoa
is
A. Motion of the electrons:
a) Specify whether B is connected to the
positive or to the negative pole of the battery.
b) Calculate the charge and the number of electrons
that enter into junction A
during 2 minutes
16
C 3A
B
D
Lo
IR
B. Grouping of lamps:
a) Name the two lamps which are connected in series.
b) Name the two lamps which are connected in parallel. Are these two lamps identical? why?
CJunction ule:
al Specify the value of the current Is that flows out of the junction B.
b) Calculate the value of the current 12.
c) Determine the direction and the value of the current 16
d) Deduce the value of the current 17.
D. Laws of voltages:
Given: UA= 12 V, UE= -2 V, UED = 1 V and Uac=5.5 V.
a) Calculate UAE, UAD, Ucend Up
b) Calculate UCD. Specify whether the lamps L3 and Ls are identical.
o) Draw the branch BE and show the connections of an oscilloscope so that it displays Urg. ground to
in) The luminous line, initially at Y=0, is displaced downward. Justify.
iii) Calculate the number of division y by which the luminous line is displaced. (given Sv = 1V/div)
phrase A

American eels (anguilla rostrata) are freshwater fish with long, slender bodies that we can treat as uniform cylinders 1.0 m long and 10 cm in diameter. an eel compensates for its small jaw and teeth by holding onto prey with its mouth and then rapidly spinning its body around its long axis to tear off a piece of flesh. eels have been recorded to spin at up to 14 revolutions per second when feeding in this way. although this feeding method is costly in terms of energy, it allows the eel to feed on larger prey than it otherwise could. 1.a field researcher uses the slow-motion feature on her phones camera to shoot a video of an eel spinning at its maximum rate. the camera records at 120 frames per second. through what angle does the eel rotate from one frame to the next? 2. the eel is observed to spin at 14 spins per second clockwise, and 10 seconds later it is observed to spin at 8 spins per second counterclockwise. what is the magnitude of the eels average angular acceleration during this time? 3. the eel has a certain amount of rotational kinetic energy when spinning at 14 spins per second. if it swam in a straight line instead, about how fast would the eel have to swim to have the same amount of kinetic energy as when it is spinning? 4.a new species of eel is found to have the same mass but one-quarter the length and twice the diameter of the american eel. how does its moment of inertia for spinning around its long axis compare to that of the american eel?

In a thunderstorm, charge builds up on the water droplets or ice crystals in a cloud. thus, the charge can be considered to be distributed uniformly throughout the cloud. for the purposes of this problem, take the cloud to be a sphere of diameter 1.00 kilometer. the point of this problem is to estimate the maximum amount of charge that this cloud can contain, assuming that the charge builds up until the electric field at the surface of the cloud reaches the value at which the surrounding air breaks down. this breakdown means that the air becomes highly ionized, enabling it to conduct the charge from the cloud to the ground or another nearby cloud. the ionized air will then emit light due to the recombination of the electrons and atoms to form excited molecules that radiate light. in addition, the large current will heat up the air, resulting in its rapid expansion. these two phenomena account for the appearance of lightning and the sound of thunder. take the breakdown electric field of air to be eb=3.00ă—106n/c. part a estimate the total charge q on the cloud when the breakdown of the surrounding air is reached. express your answer numerically, to three significant figures, using ďµ0=8.85ă—10â’12c2/(nâ‹…m2) .

The seven sisters, seven stars located more than 400 light-years away in the taurus constellation can be seen here with venus and another constellation, orion. the seven stars stay grouped together but seem to move, like the planet venus. why do stars seem to move like planets in the night sky?