Electromagnetism questions

A magnetic field has been created around the wire as shown. What direction is the current flowing in?

• Upwards
• Out of the page
• Downwards
• Into the page

Which of the following will increase the flux density of the magnetic field in the centre of this coil?

Choose all the correct answers.

• Fitting an iron core

• Increasing the current I through the coil

• Increasing the distance l between the magnetic poles

• Increasing the number of turns N

How are the magnetic domains possibly arranged inside the iron core? Choose all possible correct answers.

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Even after the magnetic field of an electromagnet has been switched off, the iron core may still retain some residual magnetism. What is this called?

• Permeability

• Reluctance

• Remanence

• Saturation

An electromagnet has a field strength (H) of 20 At/m and a core whose magnetic permeability (µ) is 5 × 10⁻³ H/m. What is the flux density (B) in the core?

• 10T

• 100T

• 0.1T

• 20B