Elementary Lessons in Electricity & MagnetismMacmillan, 1915 - 744 pages |
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Common terms and phrases
acid action alternating currents amperemeter amperes angle anode armature atoms attracted ball battery capacity carbon cell centimetres charge chemical circuit coil condenser conducting conductor copper coulombs current flows curve deflexion diamagnetic dielectric difference of potential direction discharge disk distance dynamo dynes earth electric force electrified electrified body electrolytic electromagnet electrometer electromotive electromotive-force electrons electroscope electrostatic energy equal flux galvanometer glass gramme heat Hence hydrogen induction influence machine instrument insulated internal resistance inversely kathode lamp length LESSON Leyden jar light lines of force liquid machine magnetic field magnetic force magnetic lines magnetic pole measured metal motor moving N-seeking needle negative Ohm's law ohms opposite oscillations pass placed plate platinum polarization positive produced proportional quantity of electricity repelled rotation round self-inductance shunt spark sphere square steel strength substances surface temperature thin tube turns velocity voltage volts watts wire zinc
Popular passages
Page 335 - ... of those edifices, upright rods of iron made sharp as a needle, and gilt to prevent rusting, and from the foot of those rods a wire down the outside of the building into the ground, or down round one of the shrouds of a ship, and down her side till it reaches the water?
Page 334 - Would not these pointed rods probably draw the electrical fire silently out of a cloud before it came nigh enough to strike, and thereby secure...
Page 347 - The unit difference of magnetic potential exists between two points, when it requires the expenditure of one erg of work to bring a unit magnetic pole from one point to the other against the magnetic forces.
Page 240 - According to it, the equivalent weights of bodies are simply those quantities of them which contain equal quantities of electricity, or have naturally equal electric powers; it being the ELECTRICITY which determines the equivalent number, because it determines the combining force. Or, if we adopt the atomic theory or phraseology, then the atoms of bodies which are equivalents to each other in their ordinary chemical action have equal quantities of electricity naturally associated with them.
Page 250 - Tuscany that when a portion of muscle of a frog's leg, hanging by a thread of nerve, bound with silver wire, was held over a copper support so that both nerve and wire touched the copper, the muscle immediately contracted.
Page 347 - ... currents in the neighbourhood, without the presence of a magnet. Since the peculiarity of the magnetic field consists in the presence of a certain force, we may numerically express the properties of the field by measuring the strength and direction of the force, or, as it may be worded, the intensity of the field and the direction of the lines of force.
Page 334 - I say, if these things are so, may not the knowledge of this power of points be of use to mankind, in preserving houses, churches, ships, etc., from the stroke of lightning, by directing us to fix, on the highest parts of those edifices, upright rods of iron made sharp as a needle, and gilt to prevent rusting, and from the foot of those rods a wire down the outside of the building into the ground, or down round one of the shrouds of a...
Page 276 - The unit of surface is the square centimetre. Volume. — The unit of volume is the cubic centimetre. Velocity. — The unit of velocity is the velocity of a body which moves through unit distance in unit time, or one centimetre per second.
Page 332 - He proposed, therefore, to fix a pointed iron rod to a high tower, but shortly after succeeded in another way. He sent up a kite during the passing of a storm, and found the wetted string to conduct electricity to the earth, and to yield abundance of sparks. These he drew from a key tied to the string, a silk ribbon being interposed between his hand and the key for safety. I,eyden jars could be charged, and all other electrical effects produced, by the sparks furnished from the clouds. The proof...
Page 61 - Wimshurst machine. Answer. Silvanus Thompson describes it as follows: In this, the most widely used of influence machines, there are no fixed field-plates. In its simplest form it consists of (Fig. 23) two circular plates of varnished glass. which are geared to rotate in opposite directions. A number of sectors of metal foil are cemented to the front of the front plate and to the back of the back plate ; these sectors serve both as carriers and as inductors. Across the front is fixed an uninsulated...