Ampere's Law

Can currents outside the loop be considered when calculating the circulation for Ampère's law?

• Yes, all currents must be considered.

• No, only currents inside the loop affect the circulation.

• Yes, but only if they are in close proximity to the loop.

• No, unless the currents are parallel to the loop.

According to the example provided, what is the value of the integral of B·dℓ for a loop outside the current?

• The integral is not zero and depends on the distance from the current.

• The integral is equal to the current I.

• The integral is zero.

• The integral is infinite.

What should a good Amperian loop contain when using Ampère's law to find the magnetic field B?

• The point where you want to find B and it should respect the symmetry of the problem

• Any random point in the space and it should be oriented in any direction

• The point where you want to find B but symmetry of the problem is not necessary

• Only the symmetry of the problem is important, not the location of the point

When applying Ampère's law, the circulation in terms of B ( ∮ B · dℓ ) should be set equal to what other term to solve for B?

• ∮ E · dℓ

• (circ = μ₀I_enclosed)

• ∮ P · dℓ

• (circ = ε₀I_enclosed)

What is the expression for the magnetic field B at a distance r from an infinite straight wire carrying current I?

• B = μ₀I / 2πr

• B = μ₀I / πr

• B = 2μ₀I / πr

• B = μ₀I / r

What is the current density J inside an infinite straight wire carrying a uniform current I?

• J = I / πr²

• J = I / πR

• J = I / πR²

• J = πI / R²

According to the learning material, what is the condition for a solenoid to be considered infinite?

• L < R

• L = R

• L > R

• L >> R

For an ideal solenoid that is infinitely long and very tight, what is the value of B_out?

• B_out is very strong

• B_out is very weak

• B_out = 0

• B_out is equal to B inside the solenoid

What is the expression for the magnetic field B inside a solenoid with current I, turns per length n, and permeability of free space μ₀?

• B = μ₀nI

• B = μ₀I/n

• B = n/μ₀I

• B = I/μ₀n

What does the uniform field inside a solenoid imply about the magnetic field B? (Side Note: For an Ideal Tightly Packed Infinite Solenoid with L>>R)

• It varies with the position of the ab side of the loop.

• It is strongest at the center of the solenoid.

• It is the same at any position inside the solenoid.

• It only exists at the ends of the solenoid.