A 20.0 m long cylinder is sliced along its long axis to form a half-cylinder, flat on one side with a semi-circular cross section of radius 5.00 m. The half-cylinder is oriented with its long axis parallel to a long wire carrying a current of 240.0 A. The flat side of the half-cylinder is parallel to a line drawn radially outward from the wire and the nearest edge of the half-cylinder is located 1.00 cm from the wire. What is the magnetic flux through the curved surface of the half-cylinder (excluding the flat side)? T.m2
Remember when we draw magnetic field lines, we draw them so that the density of the lines in a given drawing represents the strength of the field at every location in the drawing. Therefore, if we draw a surface in a non-uniform magnetic field in which the field is stronger where it enters the surface, the number of magnetic field lines must equal the number of electric field lines. the number of magnetic field lines entering the surface must be greater than the number leaving the surface. the number of magnetic field lines entering the surface must be equal to the number leaving the surface. the number of magnetic field lines entering the surface must be less than the number leaving the surface.
The simplest magnetic structure that can exist is a magnetic dipole. a magnetic current. a magnetic quadrupole. a magnetic monopole.
A small sphere is placed halfway between the poles of a horseshoe magnet. One side of the magnet is then enclosed by a small rectangular box which includes the sphere and one side of the magnet, but not the other side. The entire combination of magnet, sphere, and small box is then placed inside a large cube. Rank the amount of total magnetic flux through each container, in order of increasing flux. cube, box, sphere The net flux is the same through each container. box, sphere, cube sphere, box, cube
Assume the magnetic field declination at your location is 22 degrees east of north. How should you orient a current carrying wire near a compass so that the compass will point directly toward geographic north, assuming the wire produces a field strong enough to deflect the compass? The wire should be horizontal and placed north of the compass. The wire should be horizontal and placed east of the compass. The wire should be vertical and placed north of the compass The wire should be horizontal and placed west of the compass.
While on a camping trip, you determine which direction is north by making nighttime observations of the North Star, Polaris, which lies within one degree of the direction of the Earth's axis. In the morning, you read your compass by daylight and find it points more than twenty degrees away from the direction you identified as north the night before. What happened? You did not account for the effect of sunlight on a compass, which will change its direction. You did not account for magnetic field declination in comparing the compass reading to geographic north. You did not account for diurnal variation, in which the direction of the magnetic field changes from night to day. You did not account for magnetic field inclination.
Which is the best description of the Earth's magnetic field? It is approximately that of a dipole, with its axis perpendicular to the Earth's rotation axis. It is a uniform field parallel to the Earth's rotation axis. It is a dipole aligned with the Earth's rotation axis. It is approximately that of a dipole, with its axis oriented at about 11 degrees to the Earth's rotational axis.
Which of these produces a magnetic field having about the same general shape as the magnetic field of the earth? All of these choices produce the same general shape. A single current loop. A proton moving in a circular path. A simple bar magnet.
What the meaning of “field inclination” is as applied to the magnetic field of the Earth? The movement of the location of Earth's geomagnetic pole over the course of a year. The angle between the direction to geographic north and the vertical component of the Earth's magnetic field. A correction that must be applied to instruments in order to measure the strength of the magnetic field while outdoors. The angle between the direction to geographic north and the horizontal component of the Earth's magnetic field.
Which instrument can measure both the magnitude and direction of a magnetic field? Dip meter. Magnetometer. Compass. Magnetron.
The vertical component of the Earth's magnetic field is usually measured by using a degaussing device. a magnetron. a dip meter. a compass.
What is a "lodestone"? Naturally occurring stone which has become magnetized. A device used as a counterweight in a magnetometer. One of the handful of large, magnetic stones which create the Earth's magnetic field. A type of stone which can be magnetized by an electromagnet.
Which of the following is evidence that the Earth's magnetic field reverses direction roughly every million years or so? Ancient writings from cave men. The Earth's magnetic field NEVER reverses direction. Alternating directions of magnetization in the rocks solidified at different times near the mid-Atlantic Ridge. We see a reversing electric field caused by the magnetic field.
Regions of the sea floor on either side of the Mid-Atlantic Ridge are found to be about 19 km wide and to contain magnetic rocks which have a magnetic field mostly aligned with the current direction of the Earth's magnetic field, while rocks farther out from the ridge have fields which point in the opposite direction. If the oldest rocks in the 19 km wide strip are about 750,000 years old, what has been the average speed of the sea floor expansion during this time? m/s
The strength and direction of the Earth's magnetic field at some locations never change. changes significantly every year. changes significantly many times per day. may change significantly over hundreds of years.
Which of these is the best approximation to the form of the Earth's magnetic field? A magnetic monopole. A magnetic quadrupole. A magnetic dipole. A magnetic octopole.
While on a hike in the North Cascades National Park in the state of Washington, where the magnetic field declination is 17.0 degrees, you want to reach a campsite which is 28.3 km due north of your current position. You look at your compass, and walk 28.3 km in the direction the compass points but after walking the full distance, the campsite is nowhere in view. How far south are you from the campsite? km
The geomagnetic north pole of the Earth (in the northern hemisphere) is a north magnetic pole. is located precisely at the same location as the geographic north pole. is a south magnetic pole. is located precisely at the same location as the geographic south pole.
How is the axis of the Earth's magnetic field oriented relative to the planet's rotation axis? The two axes intersect at a 45 degree angle. The two axes lie in similar directions but differ by several degrees. The two axes are perpendicular. The two axes are identical.
What gives the Earth its magnetic field? The liquid core of the Earth churning and moving charged metals. There is no inherent property that gives the Earth its magnetic field Charged radiation from the sun interacting with the Earth's atmosphere.
Which is the best description of the Earth's magnetic field? It is a uniform field parallel to the Earth's rotation axis. It is a dipole aligned with the Earth's rotation axis. It is approximately that of a dipole, with its axis perpendicular to the Earth's rotation axis. It is approximately that of a dipole, with its axis oriented at about 11 degrees to the Earth's rotational axis.
A magnetometer measures the horizontal component of the Earth's magnetic field in your location to be 60 μT. If the magnetic inclination in your location is 73 degrees and the magnetic declination is 31 degrees, what is the magnitude of the Earth's magnetic field at your location? 120 μT 210 μT 70 μT 63 μT
Which of these produces a magnetic field having about the same general shape as the magnetic field of the earth? A single current loop. All of these choices produce the same general shape. A proton moving in a circular path. A simple bar magnet.
The magnetic field declination at your location is 19.0 degrees east of north and the inclination is 71.0 degrees. If the magnitude of the Earth's magnetic field is 0.0600 mT at your location, how much current must flow in a long vertical wire placed 1.00 cm from the compass in order to make the compass point in the direction of geographic north? (Ignore the size of the compass compared to its distance from the wire and assume the compass is in a uniform magnetic field given by the value of the field 1.00 cm from the wire.) amperes.
A magnetometer measures the vertical component of the Earth's magnetic field in your location to be 60 μT. If the magnetic inclination in your location is 73 degrees and the magnetic declination is 31 degrees, what is the magnitude of the Earth's magnetic field at your location? 63 μT 120 μT 70 μT 210 μT
If the earth's magnetic field were a perfect dipole, the field inclination and declination would be zero everywhere. would be equal to each other at every location on earth. would be twice what they actually are. would depend only upon geometry.
The time it takes for a radio signal from the Cassini orbiter to reach Earth is at most 85 min. With this one-way travel time, calculate the distance Cassini is from Earth. 2.6 × 1010 m 1.5 × 1011 m 1.5 × 1012 m 5.9 × 104 m
There is an electromagnetic wave traveling in the -z direction in a standard right-handed coordinate system. What is the direction of the electric field, E⃗ , if the magnetic field, B⃗ , is pointed in the +x direction? -x direction +y direction +x direction -y direction -z direction +z direction
VHF (very high frequency) television antennas were horizontal, this means that the antenna is sensitive to signals polarized horizontally. in circles around the antenna. vertically. normal to the antenna in the forward direction.
A polarizing sheet is placed in front of a laser pointer. If the polarizing sheet is rotated through 180∘ , it is observed that the brightness of the laser dot appears to change during the rotation. We can conclude that the laser is polarized. changing its brightness. monochromatic. unpolarized.
When vertically polarized light is incident on a sheet of polarizing material with a transmission axis oriented vertically, percent of the light is transmitted through the material.
The direction of polarization is defined as the direction of the direction of the Poynting vector. the electric field vector. the direction of propagation. the magnetic field vector.
A polarizing sheet is placed in front of a neon sign. If the polarizing sheet is rotated through 180∘ , it is observed that the brightness of the neon sign does not change during the rotation. We can conclude that the sign is unpolarized monochromatic. polarized. changing its brightness.
An unpolarized beam of light has an intensity of 9000 W/m2. It is incident on a single polarizing sheet. What is the intensity of light emerging from the polarizer? 2250 W/m2 9000 W/m2 18000 W/m2 4500 W/m2
A polarizing sheet is placed in front of a computer LCD screen showing a static image. If the polarizing sheet is rotated through 180∘ , it is observed that the brightness of the screen appears to change during the rotation. We can conclude that the screen is unpolarized. changing its brightness. monochromatic. polarized.
VHF (very high frequency) television antennas were horizontal, this means that the antenna that broadcast the signal is mounted vertically. in circles around the antenna. horizontally. normal to the antenna in the forward direction.
Light from an incandescent lamp is polarized vertically. polarized at some angle in between 0 degrees and 90 degrees. unpolarized. polarized horizontally.
When unpolarized light is incident on a sheet of polarizing material with a transmission axis oriented vertically, percent of the light is transmitted through the material.
A 1-A current is used to charge a parallel plate capacitor. A large square piece of paper is placed between the plates and parallel to them so it sticks out on all sides. The value of the integral B•ds around the perimeter of the paper is: 2 T•m 4π × 10-7 T•m 8.85 × 10-12 T•m 10-7 T•m not determined from the given quantities
A 0.70-m radius cylindrical region contains a uniform electric field that is parallel to the axis and is increasing at the rate 5.0×1012 V/m•s. The magnetic field at a point 1.2 m from the axis has a magnitude of: 0 T 7.0 × 10-6 T 1.1 × 10-5 T 2.3 × 10-5 T 2.8 × 10-5 T
A current of 1 A is used to charge a parallel plate capacitor with square plates. If the area of each plate is 0.6 m2 the displacement current through a 0.3 m2 area wholly between the capacitor plates and parallel to them is: 2 A 1 A 0.7 A 0.5 A 0.25 A
A 1.2-m radius cylindrical region contains a uniform electric field along the cylinder axis. It is increasing uniformly with time. To obtain a total displacement current of 2.0 × 10-9 A through a cross section of the region, the magnitude of the electric field should change at a rate of: 5.0 V/m⋅s 12 V/m⋅s 37 V/m⋅s 50 V/m⋅s 4.0 × 107 V/m⋅s
An electron in a hydrogen atom moves in a circle of radius 1.1 × 10-10 m at a speed of about 1.6 × 106 m/s. What is the magnetic dipole moment of this electron due to its orbital motion? 9.3 × 10-24 J/T 1.4 × 10-23 J/T 1.9 × 10-23 J/T 2.8 × 10-23 J/T 3.5 × 10-23 J/T
At what rate (V/s) must the potential difference between the plates of a parallel-plate capacitor with a 1.20 µF capacitance be changed to produce a displacement current of 2.40 A? 2.00 × 106 8.14 × 106 5.67 × 106 3.10 × 106 4.23 × 106 4.92 × 106 7.12 × 106 6.15 × 106 9.37 × 106 3.87 × 106
A magnet in the form of a cylindrical rod has a length of 4.90 cm and a diameter of 0.920 cm. It has a uniform magnetization of 4.40 × 103 A/m. What is the magnetic dipole moment (J/T)? 1.43 × 10-2 4.32 × 10-3 6.14 × 10-3 9.21 × 10-3 3.07 × 10-2 8.18 × 10-3 4.12 × 10-2 7.67 × 10-3 5.24 × 10-3 5.11 × 10-2
A transmitter consists of an LC circuit with an inductance of 15 µH and a capacitance of 23 pF. What is the wavelength of the electromagnetic waves it emits? 29 mm 65 mm 5.6 m 35 m 220 m
When the distance between a point source of light and a light meter is reduced from 6.0 m to 2.0 m, the intensity of illumination at the meter will be the original value multiplied by: 1/9 9 3 1/3 1
A clear sheet of polarizing material is placed on top of a second, similar sheet so that their polarizing axes make an angle of 30◦ with each other. The ratio of the intensity of emerging light to incident unpolarized light is: 1:4 1:3 1:2 3:4 3:8
An electromagnetic wave travels in the positive direction of a z axis, with the electric fields oscillating parallel to the x axis. The rms value of the electric fields is 7.40 × 10-5 V/m and the wavelength is 300 nm. In the following equation for the electric component of the wave, what goes in the second underscored blank for the angular wave number (m-1)? Ex = _sin(_z__t) 9.85 × 108 3.77 × 107 1.05 × 107 6.18 × 107 4.97 × 107 2.09 × 107 4.24 × 108 8.12 × 107 1.20 × 108 9.02 × 108
A Gaussian surface in the shape of a right circular cylinder with end caps has a radius of 17.5 cm and a length of 84.5 cm. Through one end there is an inward magnetic flux of 28.1 μWb. At the other end there is a uniform magnetic field of 1.39 mT, normal to the surface and directed outward. What are the (a) magnitude and (b) direction (inward or outward) of the net magnetic flux through the curved surface? (a) Number Units (b)
A capacitor with parallel circular plates of radius R = 2.40 cm is discharging via a current of 20.0 A. Consider a loop of radius R/3 that is centered on the central axis between the plates. (a) How much displacement current is encircled by the loop? The maximum induced magnetic field has a magnitude of 11.0 mT. At what radius (b) inside and (c) outside the capacitor gap is the magnitude of the induced magnetic field 2.60mT? (a) Number Units (b) Number Units (c) Number Units
A charge q = 6.0 × 10-8C is distributed uniformly around a thin ring of radius r = 7.2 cm. The ring is rotating about an axis through its center and perpendicular to its plane, at an angular speed ω = 650 rad/s. What is the magnitude of the magnetic moment of the rotating charge? Number Units
The maximum electric field 9.4 m from a point light source is 1.7 V/m. What are (a) the maximum value of the magnetic field and (b) the average intensity of the light there? (c) What is the power of the source? (a) Number Units (b) Number Units (c) Number Units
A small spaceship whose mass is 1400 kg (including an astronaut) is drifting in outer space with negligible gravitational forces acting on it. If the astronaut turns on a 11 kW laser beam, what speed will the ship attain in 3.0 days because of the momentum carried away by the beam? Number Units
In the figure, a light ray in air is incident on a flat layer of material 2 that has an index of refraction n2 = 4.4. Beneath material 2 is material 3 with an index of refraction n3. The ray is incident on the air-material 2 interface at the Brewster angle for that interface. The ray of light refracted into material 3 happens to be incident on the material 2-material 3 interface at the Brewster angle for that interface. What is the value of n3? Number Units
The intensity of sunlight near the surface of the Earth is approximately 1.00 × 103 W/m2. What would be the side length (m) of a square mirror that would feel a 1.00 N force from sunlight when held so the plane of the mirror was perpendicular to the path of the light? Number Units
A ray of light in air enters a 1.00 - cm thick pane of glass at a 50◦ angle to the surface normal. The sides of the glass are parallel to each other. The light emerges from the other side displaced 0.615 cm from the place it would have emerged if it did not refract. What is the index of refraction of the glass? 1.28 1.46 1.72 1.59 1.35 1.94 1.65 1.14 1.41 1.53