Resource 4: Workcards

WORKCARD 1: HEAT

What you have:

• a torch cell/a torch bulb
• a 10 cm length of very very thin, bare wire (unravelled from wire flex from an old broken tape recorder) or fuse wire
• a 10 cm length of ordinary bare copper wire

What you do:

• Hold the 10 cm wire with the two ends on the top and bottom of the torch cell.
• Touch the arc of the wire to the back of someone’s hand. Do they feel anything?
• Repeat using the length of very very thin wire/or fuse wire. Do they feel anything now?
• What form of energy do you sense here?
• Discuss what you have felt. Try to think of an explanation of your own. Experiment using the different wires to light the bulb. Compare the brightness. What do you think?

WORKCARD 2: MAGNETISM

What you have:

• a torch cell
• a 30 cm length of insulated copper wire
• a large soft iron nail
• some metal objects – pins, tacks, etc.
• iron filings
• a small compass

What you do:

• First check to see if the large soft iron nail has any effect on the pins, tacks, iron filings and compass.
• Wrap the wire around the large soft iron nail many times.
• Hold the two bare ends against the terminals of the torch cell.
• While it is still attached, check to see the effect on the pins, tacks, etc.
• What form of energy do you find?
• Can you get one end of the nail to ‘repel’ (push away) one end of the compass?
• What is your group’s explanation of what you see here?

What you have:

• a torch cell
• 25 cm length of insulated copper wire
• a steel needle or pin that has been magnetised (made into a magnet) by being placed alongside a strong magnet for a time
• a 15 cm strip of thin, flexible card
• a small electric motor from an old broken toy or tape recorder
• a drawing pin

What you do:

• Make a tight coil by wrapping the wire around a pencil.
• Fasten the strip of card to the edge of the table/desk so that it is like a swimming pool diving board.
• Push the magnetised needle so that it hangs vertically from the end of the strip.
• Hold the coil steady with the magnetised needle dangling into the centre of the coil.
• Hold the torch cell with one bare end of the wire from the coil in contact with the base.
• Another person repeatedly touches the other end of the wire to the top of the cell.
• Discuss what you have seen happen. What form of energy do you find? What is your group’s explanation for what you have seen?
• Now turn the torch cell upside down and repeat the activity. But first PREDICT what you think you will see.
• Finally – use the torch cell to work the small electric motor. What direction is it spinning? Can you reverse the direction?
• Do you think an electric motor might have something to do with coils of insulated wire and magnets?

WORKCARD 4: SOUND

What you have:

• a torch cell
• small speakers from old broken electrical equipment
• grains of coarse sand/bits of wire flex

What you do:

• Experiment to see if you can get sounds from the speakers by attaching the torch cell to the speaker terminals (why are there always two?).
• You should be able to get a crackling sound.
• What do you have to do to repeat the sound?
• Sprinkle grains of coarse dry sand onto the open cone of the speaker. What do you notice as you make repeated crackling sounds?
• Look carefully at the speakers. Can you see any arrangement of magnets and coils or spirals of wire?
• Discuss your own ideas of how a speaker works.
• Can you link your ideas to Workcard 3: Movement?

WORKCARD 5: LIGHT

What you have:

• three torch cells
• four torch bulbs
• assorted lengths of flex wire

You have already seen how we get a bulb to light and you have already investigated the structure of a light bulb.

What you do:

• Investigate different arrangements for getting different numbers of torch cells to light up different numbers of bulbs.
• Record the different arrangements that work. Draw pictures to show these.
• Which were the brightest bulbs?
• Can you think of ways to explain what you see?