David Sang Solutions for Chapter: Magnetism, Exercise 4: End-of-chapter questions

A soft-iron rod and a steel rod each have coils around them. Both rods are initially un-magnetised. The coils are attached to circuits, as shown in the below diagram.

Copy the table below, referring to the soft-iron rod and the steel rod shown in the above diagram.

Use the following statements to complete the table.

Magnetised     loses its magnetism     keeps its magnetism

A soft-iron rod and a steel rod each have coils around them. Both rods are initially un-magnetised. The coils are attracted to circuits, as shown in the second diagram.

Which words apply to the force between the rods when the switches are closed? Choose one from:

no force     attractive force     repulsive force

A soft-iron rod and a steel rod each have coils around them. Both rods are initially un-magnetised. The coils are attracted to circuits, as shown in the second diagram.

Which of the two arrangement would be used as the electromagnet on the crane in a scrap metal yard?

A soft-iron rod and a steel rod each have coils around them. Both rods are initially un-magnetised. The coils are attracted to circuits, as shown in the second diagram.

State one advantage that an electromagnet could have in comparison with similar-sized permanent magnet?

State two advantages that electromagnets have, compared with permanent magnets.

For each of the lists below, choose the option that should be used to give the strongest electromagnet.

Number of turns on coil:

$1000 \mathrm{turns}$   $500 \mathrm{turns}$    $250 \mathrm{turns}$

For each of the lists below, choose the option that should be used to give the strongest electromagnet.

Type of core:

air     plastic     iron

For each of the lists below, choose the option that should be used to give the strongest electromagnet.

Current:

$3.0 \mathrm{A}$     $2.0 \mathrm{A}$     $1.0 \mathrm{A}$