15 Magnetism 2021 J&N

Diagram 1 shows a small compass needle with its poles marked. It is not near any magnetic materials. Diagram 2 shows a bar magnet with its poles marked. The compass needle is placed at point P. In which direction will the N pole of the compass needle point?

• to the left

• to the right

• down the page

• up the page

Which diagram shows the pattern and direction of the magnetic field lines around a bar magnet?

Two metal rods each have a painted end. The painted ends are placed next to the N pole and S pole of a bar magnet in turn.

What are rod 1 and rod 2 made from?

• magnetised steel, aluminium

• iron, magnetised steel

• aluminium, iron

• iron, aluminium

Three piles of small nails, P, Q and R, are placed on a bench below three electromagnets. One set of nails is made of copper, one of soft iron and one of steel. Which row correctly identifies the materials from which the nails are made?

• P - copper, Q - soft iron, R - steel

• P - copper, R - soft iron, Q - steel

• Q - soft iron, P - copper, R - steel

• Q - soft iron, R - steel, P - copper

A bar magnet picks up two steel bolts. Which diagram shows the magnetic poles induced in the bolts?

Which diagram shows the magnetic field around a bar magnet?

Which method does not demagnetise a bar magnet?

• Heat the bar magnet and place it in the east-west direction to cool.

• Place the bar magnet in the east-west direction and hammer it.

• Place the bar magnet in a coil connected to an a.c. supply and slowly withdraw it.

• Place the bar magnet in a coil connected to a d.c. supply and slowly withdraw it.

A magnet is suspended by a cotton thread.

The magnet is displaced then allowed to swing freely until it comes to rest.

Why does the magnet always come to rest pointing in the same direction?

• because of the interaction between the electric field of the magnet and the electric field of the Earth

• because of the interaction between the electric field of the magnet and the magnetic field of the Earth

• because of the interaction between the magnetic field of the magnet and the gravitational field of the Earth

• because of the interaction between the magnetic field of the magnet and the magnetic field of the Earth

A soft-iron bar is not magnetised. It is held close to the N pole of a magnet and then to the S pole of the same magnet.

What will be the result?

• attracts, attracts

• attracts, repels

• repels, attracts

• repels, repels

Three cores of different metals P, Q and R are placed inside identical coils of wire.

At least one of the metals is non-magnetic.

The cores are held above some iron nails.

The three diagrams show what happens when there is a current in the coils.

The three diagrams below show what happens when the current is then switched off.

Which core metals are magnetic?

• P only

• R only

• P and Q

• Q and R