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?

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:

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