Question 1

A beam of electrons is sent in the positive x-direction in a region with a uniform magnetic field B in the positive y-direction and a uniform electric field E in the positive z-direction.At which of the following speeds would the electrons be deflected in the positive z-direction?

Accepted Answer

The answer of A beam of electrons is sent in...

Question 2

The magnetic domains in a non-magnetized piece of iron are characterized by which orientation?

Accepted Answer

In a non-magnetized piece of iron, the magnetic domains are arranged randomly, without any preferred orientation. It is only when an external magnetic field is applied that the domains align and the iron becomes magnetized.

Question 3

Two long parallel wires 40 cm apart are carrying currents of 10 A and 20 A in the opposite direction.What is the magnitude of the magnetic field halfway between the wires?

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Question 4

Square coil A has 2N turns and sides of length L, and square coil B has N turns and sides of length 2L.When a current of 2 amps is sent through coil A and a current of 1 amp is sent through coil B, which coil has the greater magnetic moment?

Accepted Answer

The magnetic moment ($m$) of a coil is given by the product of the number of turns ($N$), the current ($I$), and the area ($A$) of the coil ($m = NIA$). For coil A, $m_A = 2N \times 2 \times L^2 = 4NL^2$. For coil B, $m_B = N \times 1 \times (2L)^2 = 4NL^2$. Thus, both coils have the same magnetic moment.

Question 5

A superconducting solenoid is to be designed to generate a magnetic field of 5.00 T.If the solenoid winding has 1 000 turns/m, what is the required current? (µ₀ = 4p * 10^-7 T*m/A)

Accepted Answer

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Question 6

A solenoid with 500 turns, 0.10 m long, carrying a current of 4.0 A and with a radius of 10^-2m will have what strength magnetic field at its center? (magnetic permeability in empty space µ₀ = 4p * 10^-7T*m/A)

Accepted Answer

The answer of A solenoid with 500 turns, 0.10 m...

Question 7

A current in a solenoid coil creates a magnetic field inside that coil.The field strength is directly proportional to:

Accepted Answer

According to Ampere's Law, the magnetic field inside a solenoid is directly proportional to the current passing through the coil. Therefore, option B is the valid choice. The area of the coil does not affect the magnetic field strength.

Question 8

A square coil and a triangular coil each have sides of length L.The triangular coil has twice as many turns as the square coil.If a the same current is sent through each coil, when the coils are placed in the same uniform magnetic field making an angle of 30^- with the planes of the coils, which coil experiences the greater torque?

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Question 9

Two parallel conductors are carrying currents in the opposite direction.The currents are non-zero and not necessarily equal.The magnitude of the magnetic field midway between them is 40 mT.If one of the currents then has its direction reversed, what is the resulting magnitude of the magnetic field midway between them?

Accepted Answer

The magnetic field between the two parallel conductors is given by:
B = (μ0*I)/(2π*d)
where μ0 is the permeability of free space, I is the current, and d is the distance between the conductors. 
Since the currents are in opposite directions, the net current is I1 - I2, where I1 and I2 are the currents in the two conductors. When we reverse the direction of one of the currents, the net current becomes I1 + I2. 
Using the equation for the magnetic field, we can see that the magnitude of the magnetic field is proportional to the net current. Therefore, when we reverse the direction of one of the currents, the magnitude of the magnetic field will decrease if the magnitudes of the two currents are not equal. This means that the new magnetic field will be less than 40 mT, leading to choice C as the best option.

Question 10

Two parallel conductors each of 0.50 m length, separated by 5.0 * 10^-3 m and carrying 3.0 A in opposite directions, will experience what type and magnitude of mutual force? (magnetic permeability in empty space µ₀ = 4p * 10^-7 T*m/A)

Accepted Answer

The formula for the magnetic force between two parallel conductors carrying current in opposite directions is:

F = μ0*I1*I2*L/(2*pi*d)

where F is the force, μ0 is the magnetic permeability of free space, I1 and I2 are the current in the conductors, L is the length of the conductors, and d is the distance between the conductors.

Plugging in the given values, we get:

F = (4*pi*10^-7)*(3 A)*(3 A)*(0.5 m)/(2*pi*5*10^-3 m)
  = 1.8*10^-4 N

The force is repulsive because the two currents are in opposite directions. Therefore, the correct answer is (D) repulsive, 1.8 x 10^-4 N.

Question 11

Superconductors can carry very large currents with no resistance.If a superconducting wire is formed into a solenoid of length 50.0 cm with 500 turns, what is the magnetic field inside the solenoid when the current is 10⁴ A? (µ₀ = 4p * 10^-7 T*m/A)

Accepted Answer

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Question 12

A current in a solenoid with N turns creates a magnetic field at the center of that loop.The field strength is directly proportional to:

Accepted Answer

According to the Biot-Savart law, the magnetic field strength at the center of a current-carrying solenoid is directly proportional to the number of turns in the loop and the current strength. Therefore, both choices A and B are valid.

Question 13

Two parallel wires are separated by 0.25 m. Wire A carries 5.0 A and Wire B carries 10 A, both currents in the same direction. The force on 0.80 m of Wire A is:

Accepted Answer

The answer of Two parallel wires are separated by 0.25...

Question 14

Consider two long, straight parallel wires, each carrying a current I.If the currents are flowing in opposite directions:

Accepted Answer

When two parallel wires carrying currents in opposite directions, they experience a magnetic force that is repulsive in nature. The force per unit length between the two wires is given by F = (μ₀I₁I₂)/(2πd) where μ₀ is the vacuum permeability, I₁ and I₂ are the currents flowing through the wires, and d is the distance between the wires. Since the currents are opposite in direction, the force between the wires is repulsive.

Question 15

Two insulated current-carrying straight wires of equal length are arranged in the lab so that Wire A carries a current northward and Wire B carries a current eastward, the wires crossing at their midpoints separated only by their insulation. Which of the following statements are true?

Accepted Answer

When two current-carrying wires cross each other, a magnetic field is produced due to the current in each wire. This magnetic field exerts a force on the other wire according to the right-hand rule. The direction of the force is perpendicular to both the magnetic field and the direction of the current. In this situation, the magnetic fields produced by the wires are perpendicular to each other, so the forces that they exert on each other are also perpendicular and cancel out. Therefore, there are forces acting on both wires, but the net force on each wire is zero.

Question 16

When an electromagnet has an iron core inserted, what happens to the strength of the magnet?

Accepted Answer

When an iron core is inserted into an electromagnet, the strength of the magnet increases because the iron core helps to concentrate the magnetic field, resulting in a stronger magnetic force.

Question 17

Solenoid #1 has a length L, cross-sectional area A, and N turns.Solenoid #2 has a length 2L, cross-sectional area 2A, and 2N turns.Which solenoid has the greater magnetic field at its center when equal currents are going through them?

Accepted Answer

The magnetic field at the center of a solenoid is given by $B = \mu_0 \frac{N}{L} I$, where $N$ is the number of turns, $L$ is the length, and $I$ is the current. For both solenoids, when the current is equal, the ratio $\frac{N}{L}$ remains constant ($\frac{N}{L} = \frac{2N}{2L}$), meaning the magnetic field strength will be the same for both.

Question 18

Two parallel wires carry the a current I in the same direction.Midway between these wires is a third wire, also parallel to the other two, which carries a current 0.5 I, but in the direction opposite from the first two wires.In which direction are the net forces on the outer wires?

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Question 19

Two parallel conductors are carrying currents in the same direction.The currents are non-zero and not necessarily equal.The magnitude of the magnetic field midway between them is 40 mT.If one of the currents then has its direction reversed, what is the resulting magnitude of the magnetic field midway between them?

Accepted Answer

The answer of Two parallel conductors are carrying currents in...

Quiz 19: Magnetism