Man's physical universe

xanabras

526 MAGNETISM AND ELECTRICITY

rents are induced in the body; but as the frequency is decreased the

amount of current which the body can stand hkewise decreases.

Strong electric shocks may cause death; but, on the other hand,

electric shocks are now being used to shock victims of anaesthesia back

and to bring patients back to sanity from the living death of

to life

mental disease.

STUDY QUESTIONS

1. Why are fuses used in all household lighting circuits?

2. What causes a fuse to blow out?

3. Explain the principle of arc lamps.

4. Why does a penny not serve as a good substitute for a fuse in a household

lighting circuit?

5. Differentiate between science and invention.

6. W'hy are gases used in some filament lamps?

7. Explain the action of the photoflash lamp.

8. Explain the so-called "neon" lamps.

9. What is the thermoelectric effect?

10. How has the development of electric lighting affected civilization?

11. Our electricity bills are rated in terms of kilowatt-hours. What measurement

is expressed in kilowatt-hours?

12. State Joule's law.

13. What is the relation between the resistance of a wire and its diameter?

14. What current will flow in a lamp whose resistance is 200 ohms when in a

110-volt circuit?

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