Electricity and Magnetism

1 Marks Question

1. What is transformer?
2. The electrical device which changes A.C. voltage to high A.C. voltage or vice-versa at a constant frequency is called a transformer.
3. Write one example of each instrument that produces less amount of electricity and large amount of electricity.
4. Cell or dynamo produces less amount of electricity and generator produces large amount of electricity.
5. What is heating element?
6. The conductor which is used over electrical appliances to convert electrical energy into heat energy is called heating element. For example: nichrome.
7. Define step up transformer.
8. The transformer which converts A.C. voltage into high A.C. voltage is called step-up transformer.
9. What is filament?
10. A coil which is made up of tungsten metal kept inside the electric bulb is called filament. It has high resistivity and high melting point about 3400°C.
11. What is dynamo? On which principle does it work?
12. The device which work on the principle of electromagnetic induction and convert mechanical energy into electrical energy is called dynamo. It works on the principle of electromagnetic induction.
13. What is the function of fluorescent powder in fluorescent lamp?
14. The function of fluorescent powder in fluorescent lamp is it convert ultraviolet ray into visible ray.
15. Mention any two methods for increasing the amount of current produced by a generator/dynamo.
16. Methods for increasing the amount of current produced by a generator are:
    
    1. Increasing the number of turnings of the coil.
    2. Using magnet with strong magnetic field.
17. On which principle does the generator work?
18. Generator works on the principle of electromagnetic induction.
19. What is electromagnetic induction? Write its one use.
20. If there is the relative motion between magnet and conduction wire there is production of alternating current in the close circuit. This phenomenon is called electromagnetic induction. It is used in dynamo.
21. What is used to laminate the core of transformer.
22. Varnish or shellac is used to laminate the core of transformer.
23. What is the unit of electricity consumption?
24. The unit of electricity consumption is Kilowatt hour (Kwh).
25. What is the magnetic effect of current electricity? Who discovered it? Define step-up transformer.
26. When an electric current is passed through a wire, a magnetic field is produced around it. This is known as magnetic effect of current. Hans Christian Oersted discovered it. The transformer which converts A.C. voltage into high A.C. voltage is called step-up transformer.
27. Which principle is dynamo based on?
28. Dynamo is based on principle of electromagnetic induction.
29. What is lighting effect of current?
30. When current is passed through a wire of high resistance, it becomes extreme hot and produce light. This effect is called lighting effect of electric current.
31. What is transformer? In which principle does it base?
32. The electrical device which changes A.C. voltage to high A.C. voltage or vice-versa at constant frequency is called transformer. It works on the principle of mutual induction.
33. What is motor effect? Write the name of any two devices which are based on motor effect?
34. When a current-carrying conductor is placed in a strong magnetic field, there is regular attraction and repulsion of magnetic poles of two magnets, by which the current-carrying conductor shows vibration. This is called the motor effect.

    The devices which are based on motor effect are electric motor, fans, washing machine, cd player etc.