Manual of Experimental Physics for Secondary Schools

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Page 64 - It is measured by the product of the force by the force arm (the force arm is the perpendicular distance from the axis of rotation to the line of direction in which the force acts).
Page 185 - No. 18 insulated copper wire, each about 2 m. long; a spring contact key; iron filings. readily be closed or broken. Furthermore, the key will automatically break the circuit and thus prevent useless action in the cell. Preliminary Directions. — Wind the wires, one on each of the two soft iron rods, so that beginning at the corresponding ends one wire will be wound on its core (the piece of soft iron) in the direction in which the hands of a clock move, and the other will be wound in the opposite...
Page 132 - ... thermometer not being correctly graduated. It will be sufficiently accurate to consider the error of the 100° point of the thermometer the same as the error of the observed boiling point. A lens or reading glass facilitates the estimation of tenths of degrees. Care must be taken to avoid parallax. thermometer. A correction " curve " should then be constructed for the thermometer, from which approximate corrections may be obtained for any reading. Thereafter both the observed and corrected readings...
Page 192 - NOTE. — The unit of electrical resistance is called the ohm and is the resistance of a uniform column of mercury 106.3 cm. long and 1 sq. mm. in area (14.4521 g. in mass) at 0° C. Directions. — a. Connect the apparatus as shown in Fig. 60, setting and using the galvanometer as directed in the Discussion, p. 186. Close the circuit through the galvanometer with 1 ohm resistance in the box and record the deflection of the two ends of the pointer. How much FIG. 60.
Page 250 - ... a' metres from the floor. Show that the point of maximum illumination on the floor lies at a distance -íL metres from the point on the floor vertically below the light. It is given that the illumination at a small area varies inversely as the square of the distance from the source of light and directly as the sine of the angle made by the rays of light with the normal to the area. Solution. Let an electric bulb hang at the point B in the ceiling. A Point С is on the floor, just vertically below...
Page 135 - Notice carefully any of the first bubbles that appear and describe any peculiarity in their behavior. Are they air or water vapor? g. As the boiling continues, note carefully any change in the character and behavior of the bubbles. Describe the change, if any is noticed. h. After the boiling has continued for a minute or two, remove the flame and notice what happens, particularly in the tubes A and B. While this action still continues, close tube C for a moment with the finger and note the result....
Page 148 - This left them just so much cooler. Evidently the same amount of heat lost by the water and calorimeter was gained by the ice and the water from the melted ice. Part of the heat was used in melting the ice; part in warming the water which resulted from melting the ice. It now remains to determine upon a unit of heat. We will adopt for our unit that amount of heat which will raise the temperature of 1 g. of water 1° C. We will call this a calorie. If one calorie will heat 1 g. of water 1° C., will...
Page 105 - ... the ratio of the ovendry weight of a sample to the weight of a volume of water equal to the volume of the sample at some specific moisture content, as green, air-dry, or ovendry.
Page 312 - The specific resistance of a substance is the resistance between opposite faces of a cube of that substance, one centimeter on each edge. In the English system a cube one inch on each edge is considered.
Page 174 - ... not enter into details, but merely remark that, in both forms of the machine, work is spent in turning the plates in opposition to electrical attractions and repulsions ; and that the mechanical energy thus consumed produces an equivalent in the form of electrical energy. 433. Electrophorus. — When electricity is required in comparatively small quantities, it is readily supplied by the simple apparatus called the electrophorus. This consists (Fig. 358) of a disc of resin, or some other material...

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