Magnetic fields in materials and electromagnetics

ferromagnetic, other materials

Magnetic Susceptibility is very high in __________ materials and negligible in _______.

No change.,

A magnetic field passes through air and enters a perfect conductor. How does the angle of the field lines change?

The field intensity decreases and bends towards the interface of the air and conductor.

A magnetic field passes through air and enters a conductor with a higher relative permeability. How does the angle of the field intensity change?

Wherever fields exist.

Where does energy/energy density exist?

Surroundings

Where is energy stored when current flows through a wire.

The resistive behavior of a circuit against change in current. The ability of a circuit to store energy in a magnetic field. The ratio of magnetic flux/current

What is inductance?

Magnetic flux. Flux measures how much magnetic field threads the loop

How do we measure the total magnetic field produced by a loop.

current

magnetic flux is directly proportional to _________

geometry and materials. (does not depend on current)

Inductance only depends on __________________

how much magnetic flux a circuit produces from its own current.

What does self-inductance measure?

A solenoid because it has more loops

Which has a larger inductance? A solenoid (with the same area as the loop) or a single loop.

doubling the number of loops (quadruples the inductance)

What would change the inductance the most? Doubling the area, doubling the length, or doubling the number of loops?

Maximize the number of turns. Minimize the total length of the inductor. Maximize the area of the loops. Place a ferromagnetic material inside.

How would you design a solenoid with a large inductance?

short circuit, electric field, voltage, open circuit

At switch closing, a capacitor behaves like ______. Builds______. Resists change in ________. And behaves like a ________ at steady state.

open circuit, magnetic field, current, short circuit

At switch closing, an inductor behaves like ______. Builds______. Resists change in ________. And behaves like a ________ at steady state.

The amount of field passing through a circuit tells it how the current is changing and will determine the magnitude of EMF.

How does a circuit know how current is changing?

Changing magnetic flux. Changing B creates voltage.

EMF is caused by____________.

Right hand rule!

How are the directions of EMF and Magnetic Flux determined?

it ensures that EMF will oppose any change in B

Why is there a negative sign in Faraday’s Law?

EMF is clockwise. Induced Current is clockwise. This will induce a B field (acting downward) that acts against the change in the external B field.

The EMF will be counterclockwise. Induced current will be counter clockwise

Yes. All that matters is the rate of change.

Can EMF be induced at the moment B = 0?

The EMF will be clockwise. The induced Current will be clockwise.

Yes. There must be. If there is changing voltage, there must be electric field.

If there is EMF, is there also an electric field?

Yes. But there is no current.

The loop gives the EMF something to do work on.

magnetic field.

Changing electric flux generates

electric field.

Changing magnetic flux leads to_________.

Yes!

Is there current in the wire?

Yes!

Is there magnetic field circulating around the wire?

Yes! There must be.

Is there magnetic field between the two plates?

No.

Is there current in the plates?

displacement current

What do we call the current produced by changing electric flux?

No. Because the electric field is opposite. No conduction current either. The B field dissapears.

When a capacitor is full charged, is there displacement current?

Yes. Use RHR to find the direction of B.

Does magnetic field exist in the space between the plates?

Yes. But it is field mediated.

Is displacement current real?