## Text Book on Wireless Telegraphy |

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### Common terms and phrases

adjusted aerial circuit alternating current ammeter amperes apparatus armature arrangement atmosphere atoms battery buzzer charged closed circuit conductor connections consists copper coupling coil crystal detectors current flows decrease decrement degree of coupling dielectric difference of potential direct current direction distance earth ebonite electric strain electrons ether waves galvanometer glass high frequency increase induction coil inductive effects insulated interlinked iron joined in series joules magnetic field magnetic lines magnetic strain Marconi maximum metres natural wave length negative number of magnetic number of turns obtained ohms ordinary oscillating circuit oscillating currents plates Poldhu poles potentiometer primary circuit quenched spark radio-telegraphy receiver aerial receiving circuit resistance secondary circuit secondary coil sensitive shown in Fig shunt signals spark gap station surface switch take place Telefunken telegraphy telephone receivers terminals transformer transmitter tube tuning undamped waves vibration voltage volts wave length wavemeter wire wireless

### Popular passages

Page 60 - ... circuit when the current is changing at the rate of one ampere per second and call this " The Coefficient of self-induction " or the " Inductance

Page 40 - X its resistance X time in seconds. In order that the student may become familiar with the methods of working electrical calculations, a few examples will now be given : — 1. A current of 5 amperes is required to drive a 100 volt motor; what is the power given to the motor, the total energy used in half an hour, and, if the efficiency of the motor is 80 per cent., what is its horse-power ? Power given to motor in watts = VC = 100 X 5 = 500 watts. Watts are joules per second, therefore energy used...

Page 31 - In this system of units the centimetre is the unit of length, the gramme is the unit of mass, and the second is the unit of time — hence the name — CGS units.

Page ii - Embracing a Complete Set of Answers to the South Kensington Papers for the years 1885-1899, and a -Series of Original Questions. With 67 Original Illustrations. Crown 8vo., 2s.

Page i - ELEMENTARY TREATISE ON ELECTRICITY AND MAGNETISM. By G. CAREY FOSTER, FRS ; and ALFRED W. PORTER, B.Sc. Founded on JOUBERT'S ' Traite Eldmentair£ d'Electricite '. With 374 Illustrations and Diagrams.

Page 15 - strength of a magnetic field" at any point is measured by the...

Page 70 - ... cycle and the number of cycles per second is called the frequency of the machine or circuit in which its current flows.

Page 60 - The coefficient of self-induction is measured in units called henrys— it a circuit has a "coefficient of self-induction "-of 1 henry, it means that when the current in the circuit is changing at the rate of 1 ampere per second there will be induced in that circuit an EMF of 1 volt. If the circuit consists of one turn of wire, the change of magnetic lines would in this case be 100,000,000 or 108 per second, if it consists of a coil of T turns the change in the number of 10* magnetic lines is -=-...

Page i - LONGMANS, GREEN, & CO., 39 Paternoster Row, London ; New York, Bombay, Calcutta, and Madras.

Page ii - MARCHANT.— ELEMENTARY QUESTIONS IN ELECTRICITY AND MAGNETISM. With Answers. Compiled by MAGNUS MACLEAN, D.Sc., MIEE, and EW MARCHANT, D.Sc., AIEE Crown 8vo., u.