A text-book of physics, largely experimentalOn the Harvard college "Descriptive list of elementary physical experiments." . rrent were not acting. At other points the force due to the current is exactly opposite indirection to the horizontal magnetic force of the earth. At suchpoints, if the force due to the current is greater than the other, theneedle will be reversed and point south. If the earths magneticforce prevails, the needle will still point north, but will vibrate lessquickly than if the current were not acting. In the diagram of the lines, points where the lines run north are to be
A text-book of physics, largely experimentalOn the Harvard college "Descriptive list of elementary physical experiments." . rrent were not acting. At other points the force due to the current is exactly opposite indirection to the horizontal magnetic force of the earth. At suchpoints, if the force due to the current is greater than the other, theneedle will be reversed and point south. If the earths magneticforce prevails, the needle will still point north, but will vibrate lessquickly than if the current were not acting. In the diagram of the lines, points where the lines run north are to be marked strong or weak,if the resultant force at thesepoints is greater or less than theearths horizontal magnetic force. Put the Daniell cell in circuit,through the commutator, with 15turns of the galvanoscope, andplace the latter so that the planeof its circle shall be east and west. Make in the note-book two lines,E and W (Fig. 257), to representhalf-size a horizontal cut throughthe middle of the the commutator so that the current shall flow from east towest on the top of the galvanoscope Fig. 256. \ 1 Fig. 257. Hold the compass about 20 cm. south of the centre of the circleon the same level, and record with an arrow-head on the diagramthe direction of pointing of the needle. Move the compass northeight stages of 5 cm. each, recording on the diagram the direction ofthe needle at each stopping-place. Then place the compass inside the circle, near to the eastern side,and murk the direction of the needle. Follow the needle, as in CURREN T S TRENG TH. 481 1 Exercise 50, and mark its direction at three or four other pointsseveral centimeters apart, until the line followed appears to becompleted. Make similar observations and record with respect to the westernside of the circle. Find, and record in words, the direction of pointing just overand just under the top of the circle. Reverse the current through the galvanoscope, by operating thecommutator, and
Size: 1534px × 1628px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectphysics
