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Minor Versionm

by Procheta Mallik


Using the given Tactivity tube, we make a periscope. Make two holes at the two opposite ends of the tube - one for light from the object and one for light to enter the eyes. Fix mirrors at both ends of the tube such that the angle at which the mirrors can be placed can be changed.

Change the angles of both the mirrors and predict the range of your view based on laws of reflection. Test your prediction using the periscope made

    • Scissors have functional sharp edges. Contact may result in injury. Always keep blades away from fingers and body. Handle with care.

  1. Take a printout of the periscope template.
    • Take a printout of the periscope template.

    • Place the four template pages as shown in the figure: page 1 next to page 2, page 3 below page 1 and page 4 below page 2.

    • Cut along the dotted line only (indicated using the green line in picture), and paste it on the tube.

      • Length of the tube - 30.6 cm

    • Paste the template on the tube using glue.

    • Cut off the extra bits, if any, using scissors.

    • Cut along the black dotted lines using scissors/cutter; the body of the periscope is now ready.

    • Take the remaining template and paste it on a cardboard sheet.

    • Cut along the dotted lines using scissors and fold along the solid bold lines.

    • Now, take the flap and fold the 'C' strip onto the 'B' strip, and 'A' strip onto the 'B' strip. You will thus get a thicker strip with three layers.

    • Paste it using glue.

    • Match and fold 'D' with respect to its colour and place it on the square, as shown in the image, and glue it.

    • Fold along the solid bold lines, as shown in the image.

    • Make sure the protractor scale is on the inner side.

    • Take a metal cap of the tube .

    • Paste the centre square of the template on the inner surface of the metal cap using glue.

    • While pasting the template on the metal cap, make sure two corners of the same square meet the circumference of the circle, as shown.

    • Take a 7 cm x 7 cm mirror and peel off the transparent sheet off the mirror. Identify the midpoint of the mirror by drawing a vertical and horizontal line using a sketch pen, or by drawing two diagonal lines.

    • These lines can be cleaned easily using a tissue paper.

    • Paste the mirror on the outer side of the same face where the flaps are attached, using white glue.

    • Follow the same procedure with the other metal cap.

    • Insert the controlling flap from inside of the tube, through the small rectangular slits made, and fix it.

    • Fix the metal cap on to the tube using glue.

    • Do the same at the other end of the tube to fix another mirror holder. And let them dry.

    • With the help of the protractor scale attached, we can measure the angle of the eyepiece mirror and the angle of the objective mirror.

    • Take a 2cm by 2cm foam piece and make small holes in it using scissors on both the sides, as shown.

    • Glue the foam onto the metal cap

    • Glue the 2cm x 2cm velcro piece on the foam.

    • Take a 12cm x 2cm hook of the velcro, and paste it on the controlling flap

    • Repeat these steps and stick velcro and its hook at the other end of the tube as well.

    • Adjust the angle of the mirror, bend the controlling flap and stick it to the velcro on the metal lid so that mirror gets fixed at the chosen angle.

    • Now, your periscope is ready.

    • Consider the lower opening as the eye piece and the other opening as the objective.

    • Place the eye piece near your eye and adjust the flap, until you see an image on the objective mirror.

    • Try varying the angle of the objective mirror and look at the image.

    • With the help of the periscope, look at an object. (Here, we are looking at the upper knob of the window)

    • Note down the angle of the eyepiece mirror and angle of the objective mirror, with the help of the protractor scale attached inside.

    • Vary the distance between the person viewing and the object; try viewing the same object again and note down the angles.

    • Keep a periscope at a certain constant height 'y' and let there be a constant distance between the periscope and the wall 'x'.

    • Fix the angle of the eyepiece mirror at 40 degrees.

    • Fix the objective mirror angle at 25 degrees.

      • Observe the wall and make a mark on the wall using a sticky note. The mark should be visible at the midpoint of the mirror.

      • Repeat this process by increasing the objective mirror angle by 5 degrees.

    • Record the angle of the mirrors and the height of the mark on the wall, in the given observation table.

    • Do not crumple the template.

    • Make sure that mirror is free from scratches.

    • Follow the lines on the template for cutting and folding.

    • Cut the tube into half and attach the two halves using a collar at the centre. This will allow one half of the periscope to be rotated 360 degrees while keeping the other half stationary.

    • Join two periscopes to make a longer one.

    • Box periscope.

    • Change in the size of the tube.

Finish Line

Attached Documents

Kailash NR

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