Question

2) Studying for the test with your friends Donald and Hillary, you are comparing the magnetism of the entire earth with the magnetism of a powerful refrigerator magnet. Donald says that the earth has more magnetism because it is so YUUUGE, while Hillary says that the refrigerator magnet has more magnetism because it is so on-point, focused and concentrated. Leaving all political convictions aside, what do you say? a. “I agree with you, Donald, the earth clearly has greater magnetism.” b. “I’m with you, Hillary, the planet has a strong gravitational field, but only a weak     magnetic field.” c. “You are both correct – for once; the earth has a huge flux, but the refrigerator magnet has a larger field strength.” d. “I’m so sorry to disagree with you both. Earth has a very large field strength, but the little magnet actually has more flux.”
3) My home computer desk sits in the front corner of my house. To my left is a window that faces straight south (that is, when I look out the window, I am looking south) and just beyond the desk to the right is another window that faces west. Each window measures 0.80 m high and 0.40 m wide. Assuming that the earth’s field has an intensity of 5.0 x 10-5 T and points straight north, how much flux does the south window catch? a. zero b. 1.6 x 10-5 Wb c. 4.5 x 10-5 Wb d. 1.0 x 10-4 Wb
4) In that same situation, what’s the flux through the west window? Use the same answer choices.
High voltage
In 1897, British physicist J. J. Thomson discovered that atoms are not solid little balls as most scientists believed. He used a complex and beautiful blown glass vacuum chamber, like this. The circular coils produce a magnetic field into the paper.
5) Thomson found that the ‘cathode rays’ streaming from the left side of the apparatus were negatively charged. (He could see where the rays hit the class in front because they made the glass glow there.) He knew they were negative because after passing through the magnetic field of the coils, the rays followed path a. a. b. b. (Don’t pick this one!) c. c.
6) He then connected the horizontal metal plates to a DC power supply to make a vertical electric field between them. By adjusting the voltage he could make the beam pass straight through along path b. He then knew the speed of the rays! (He did? Yes, he did!) When the electric force on the rays equaled the magnetic force on them, the speed of the particles in the beam must be given by a. v = rqB/m b. v = F/qB c. v = E/B d. v = %(2K/m)
7) Why is that result in the previous question so? Because a. magnetic force on a particle depends on speed, but electric force does not. b. electric force on a particle depends on speed, but magnetic force does not. c. both magnetic and electric forces on a particle depend on speed.
(To finish the story, Thomson found that no matter what metal he used for the cathode – the negative disk at the far left – the rays the metals emitted had exactly the same electric and magnetic properties. If the rays were made of atoms of the metal, as most people thought at the time, then of course the properties would change from one metal to another. But no – the properties were always the same. That means that all metals, and by extension, all atoms, have something in common, something smaller, the electron!)
8) The great planet Jupiter has a magnetic field at the cloud tops about ten times the field strength of Earth’s, about 5.0 x 10-4 T, and in the direction shown by the arrow. The sun spews out blasts of protons, called the solar wind, and those particles hurtle toward all of the planets. Which direction in the picture would the protons be pushed by Jupiter’s magnetic field? a. up, along the field. b. down, opposite the field. c. to the left. d. to the right.
9) Why do you suppose the doctor asks the patient to swipe his credit card through the reader? Moving the card quickly a. gets all of the information read in time, as the computer    circuitry has only a short time to read the data. b. generates a greater magnetic flux in the read coils, so    the data can be read more accurately. c. induces a greater voltage in the read coils, so the data   can be read more accurately.
10) The previous question connects most directly with a. Ampere’s Law. b. Faraday’s Law. c. Maxwell’s work. d. Ohm’s Law. e. Volta’s work.
My wife Linda and I spent a wonderful week on the tiny Scottish isle of Iona in the summer of 2015. I snapped this photo of the last utility pole on one end of the island, near the last farmhouse. The high-voltage power lines come in from the left; I darkened them to make them more visible. They connect to the large grey transformer on the pole, and from there, two other wires go on to the house.
The voltage into the transformer is probably around 10,000 V, stepped down to the output of 240 V to operate the appliances in the house.
Suppose that if everything is turned on in the house at once, the total current from the transformer reaches 80 A.
11) If the primary (input) side of the transformer has 4,000 coils or loops of wire, how many loops make up the secondary (output) side? a. 42 b. 96 c. 240 d. 2,400,000
12) Since the output current is 80 A at 240 V, what current must move in to the transformer on the high voltage side? About a. 0.5 A. b. 2 A. c. 3,300 A. d. 19,200 A.
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Perhaps you have heard of or seen induction cooktops, another great application of the principles from our course. A large alternating current (AC) circuit moves in conductors just under the glass surface of the cooktop. The changing flux induces a current in the metal pan that heats the pan and the food it in, but the cooktop itself stays cool. In this picture, the half of the block of cheese in the cut-across pan melts, but the other half that hangs out of the pan does not.
13) What would happen if you used a glass pan, instead of a metal one? a. Nothing at all; the glass pan would not heat at all. b. A glass pan would work, but more slowly, since glass    conducts heat poorly. c. A glass pan would work perfectly well, since the flux    would easily penetrate into the food.
14) What would happen if the cooktop were energized with steady, constant direct current (DC)? a. Nothing at all; no matter what kind of pan, it would not heat at all. b. The food would cook more quickly because DC is a steady and constant energy source. c. The cooktop would work just the same as with AC, if the voltage and current were the same.
A metal ring (N = 1), fully immersed in a magnetic field B of 0.15 T into the paper, has a radius of 5.0 cm. It is jerked to the right, as shown, so that it has completely left the field in just 0.0020 s.
(Remember that the area of a circle is given by ðr2.)
15) What’s the flux through the ring, while fully in the field, as shown? a. zero b. 0.00038 Wb c. 0.0012 Wb d. 0.024 Wb
16) What voltage is induced in the ring as it leaves the field? a. zero b. 0.19 V c. 0.60 V d. 12 V
17) In which direction will the induced current (if any) move in the ring as it leaves the field? a. There is no current, so no direction can be specified. b. Clockwise. c. Counter-clockwise.
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18) Here you see a simple circuit with an AC power source in series with an inductor and a light bulb. Which changes would make the bulb glow most brightly? a. Decrease the frequency of the source, increase the inductance. b. Decrease the frequency of the source, decrease the inductance. c. Increase the frequency of the source, increase the inductance. d. Increase the frequency of the source, decrease the inductance.
19) In that same circuit, suppose the source frequency equals 60 Hz, and the inductance, 2.0 mH. What is the inductor’s reactance? a. 740 Ù b. 120 Ù c. 0.75 Ù d. 0.12 Ù
20) Suppose we replace the AC source with a (DC) battery. What happens to the current in the circuit as time passes? The current a. stays the same at all times, since we are using DC. b. surges when first connected and then quickly drops to zero. c. equals zero when first connected and then quickly rises to a    final value.
21) Mark the letter A for item 21 so I know which version of the test you took. Put your test on the front table, and put your answer sheet in the shallow tray marked A at the left side of the table.

21) Mark the letter A for item 21 so I know which version of the test you took. Put your test in the crate on the side table, and put your answer sheet in the shallow tray marked A to the left of the crate. Please exit by the door at the right front of the classroom so as to minimize disruption to other students.

Answer 1

2) Studying for the test with your friends Donald and Hillary, you are comparing the magnetism of the entire earth with the magnetism of a powerful refrigerator magnet. Donald says that the earth has more magnetism because it is so YUUUGE, while Hillary says that the refrigerator magnet has more magnetism because it is so on-point, focused and concentrated. Leaving all political convictions aside, what do you say?

a. “I agree with you, Donald, the earth clearly has greater magnetism.”
b. “I’m with you, Hillary, the planet has a strong gravitational field, but only a weak magnetic field.”
c. “You are both correct – for once; the earth has a huge flux, but the refrigerator magnet has a larger field strength.”
d. “I’m so sorry to disagree with you both. Earth has a very large field strength, but the little magnet actually has more flux.”

Ans : b. “I’m with you, Hillary, the planet has a strong gravitational field, but only a weak magnetic field.”
A junkyard magnet is as powerful (about 1 T), but a refrigerator magnet is several hundred times smaller (5 mT) and the earth's magnetic field varys from about 30 μT at the equator to about 70 μT at the poles

Pls post other ques separately.