Question 1

Do like magnetic poles repel or attract?

Accepted Answer

repel

Question 2

An electron enters the velocity selector of a mass spectrometer in the direction shown Figure 19-1.

If it emerges along the path shown, which plate (A or B) has the higher potential?

Accepted Answer

Plate B

Question 3

A 14. Coulomb charge is moving straight toward you at 4800. m/s. When it is 70. meters away from you, what is the magnitude of the magnetic field it produces at YOUR location?

Accepted Answer

Zero. (The field is zero directly in front of and behind the charge.)

Question 4

If you find yourself in a locality where the magnetic declination is "15.° East," in which direction is true North in relation to a compass needle?

Accepted Answer

The answer of If you find yourself in a locality...

Question 5

Magnetic field lines come out of the south pole of a magnet and enter at the north pole.

Accepted Answer

Magnetic field lines come out of the north pole of a magnet and enter at the south pole.

Question 6

Breaking a bar magnet in half will produce

Accepted Answer

When a bar magnet is broken in half, each half becomes a new bar magnet with its own north and south poles. Magnetic monopoles do not exist in isolation; instead, breaking a magnet simply results in two smaller dipole magnets.

Question 7

A charged particle moves and experiences no magnetic force. From this we can conclude that

Accepted Answer

A charged particle will experience no magnetic force if it is moving parallel to the magnetic field or if there is no magnetic field present. Moving at right angles to the field would result in the maximum force, not zero force. The mass of the particle is irrelevant to whether it experiences a magnetic force.

Question 8

Consider a magnetic field pointing out of this page, as shown in Figure 19-1.

An electron moving on the page toward the right will

Accepted Answer

The answer of Consider a magnetic field pointing out of...

Question 9

At a particular instant, an electron moves eastward in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

Accepted Answer

The magnetic force on a moving charge in a magnetic field is given by the right-hand rule, which states that if you point your fingers in the direction of the velocity of the charge (eastward for the electron) and curl them towards the direction of the magnetic field (downward), your thumb will point in the direction of the force on a positive charge. Since an electron is negatively charged, the force will be in the opposite direction to what the right-hand rule predicts, which is southward.

Question 10

A charged particle moves with a constant speed through a region where a uniform magnetic field is present. If the magnetic field points straight upward, the magnetic force acting on this particle will be maximum when the particle moves

Accepted Answer

The magnetic force on a charged particle is given by the cross product of the velocity of the particle and the magnetic field. This force is maximum when the angle between the velocity vector and the magnetic field vector is 90 degrees, which corresponds to the particle moving horizontally when the magnetic field is vertical.

Question 11

After landing on an unexplored Klingon planet, Spock tests for the direction of the magnetic field by firing a beam of electrons in various directions and by observing the following:
Electrons moving upward feel a magnetic force in the NW direction;
Electrons moving horizontally North are pushed down;
Electrons moving horizontally South-East are pushed upward.
He naturally concludes that the magnetic field at this landing site is in which direction?

Accepted Answer

The answer of After landing on an unexplored Klingon planet,...

Question 12

At a particular instant, a proton moves Eastward in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

Accepted Answer

The magnetic force on a moving charge is given by the right-hand rule. With the velocity of the proton directed East and the magnetic field directed downward, the force is directed Northward.

Question 13

A charged particle moves with its velocity perpendicular to a magnetic field. The field acts to change the particle's

Accepted Answer

When a charged particle moves perpendicular to a magnetic field, the magnetic force acts as a centripetal force, changing the direction of the particle's velocity but not its magnitude. This results in a circular or spiral motion without a change in the particle's speed, energy, mass, magnitude of momentum, or charge.

Question 14

In a pair of accelerating plates, such as found inside a CRT, the electrons are emitted

Accepted Answer

Electrons, being negatively charged, are emitted from the negatively charged cathode and accelerate towards the positively charged anode in a CRT (Cathode Ray Tube).

Question 15

When a voltage is applied for display on an oscilloscope CRT, it is usually shown on the screen plot

Accepted Answer

When a voltage is applied for display on an oscilloscope CRT, it is typically shown on the screen plot vertically. The horizontal axis usually represents time, while the vertical axis represents the voltage level.

Question 16

A mass spectrometer needs

Accepted Answer

A mass spectrometer uses perpendicular magnetic and electric fields to separate ions based on their mass-to-charge ratio.

Question 17

A proton, moving in a uniform magnetic field, moves in a circle perpendicular to the field. If the proton's speed tripled, its time to go around its circular path would be

Accepted Answer

The time to go around the circular path, or the period, of a charged particle in a uniform magnetic field is independent of its speed. This is because while the speed affects the radius of the circular path, the period is determined by the charge and mass of the particle and the strength of the magnetic field, none of which change when the speed changes.

Question 18

A charged particle is observed traveling in a circular path in a uniform magnetic field. If the particle had been traveling twice as fast, the radius of the circular path would be

Accepted Answer

The answer of A charged particle is observed traveling in...

Question 19

What happens to the cyclotron frequency of a charged particle if its speed doubles?

Accepted Answer

The answer of What happens to the cyclotron frequency of...

Question 20

The magnetic moment of a current loop does not depend upon

Accepted Answer

The magnetic moment of a current loop depends on the current flowing through the loop and the area of the loop but not on the external magnetic field. It is given by the product of the current and the area of the loop.

Quiz 19: Magnetism