AIM OF THE EXPERIMENT: To show how an epidiascope works.
MATERIALS: a shoebox, a magnifying glass, scissors, a grown-up helper, a table, sticky tape, modelling clay, a piece of card the size of a postcard, a torch.
MATERIALS: a shoebox, a magnifying glass, scissors, a grown-up helper, a table, sticky tape, modelling clay, a piece of card the size of a postcard, a torch.
Изображение
Ask the grown-up to cut a round hole the size of the magnifying glass in one side of the box.
Fit the magnifying glass into the hole and hold it there with the sticky tape.
Stand the box on the table.
Make a screen out of the card, stand it on the table a little way from the box, facing the lens in the hole, and hold it up with the modelling clay.
Inside the box, against the wall with the hole in it but in the other corner, lay the torch so that it lights the opposite wall of the box (see the picture).
Darken the room, switch the torch on and put your hand into the box, under its beam and opposite the magnifying glass.
Move the box about in front of the screen until a sharp image of your hand appears on it.
Wiggle your fingers.
RESULTS: The screen shows an image of your hand, in colour and moving, but upside down.
WHY? Light from the torch reflects off your hand and passes through the magnifying glass. The lens gathers this light and focuses it on the screen. If there is an object or a picture at the focus of the lens, its image is projected onto the screen. Light travels in straight lines, but it changes direction in the lens, and so the image on the screen comes out upside down.
METHOD:
Fit the magnifying glass into the hole and hold it there with the sticky tape.
Stand the box on the table.
Make a screen out of the card, stand it on the table a little way from the box, facing the lens in the hole, and hold it up with the modelling clay.
Inside the box, against the wall with the hole in it but in the other corner, lay the torch so that it lights the opposite wall of the box (see the picture).
Darken the room, switch the torch on and put your hand into the box, under its beam and opposite the magnifying glass.
Move the box about in front of the screen until a sharp image of your hand appears on it.
Wiggle your fingers.
RESULTS: The screen shows an image of your hand, in colour and moving, but upside down.
WHY? Light from the torch reflects off your hand and passes through the magnifying glass. The lens gathers this light and focuses it on the screen. If there is an object or a picture at the focus of the lens, its image is projected onto the screen. Light travels in straight lines, but it changes direction in the lens, and so the image on the screen comes out upside down.
METHOD: