Q18. We could not see element in electrical appliances. Give reason.
Q19. Why a fused bulb does not glow?
Q20. Sometimes the cells are placed side by side. Then how are the terminals of the cells connected?
Q21. Why should we look for ISI mark on electrical appliances?
Q22. On what factors does the heat produced in a wire depend?
Q23. What is battery? How can it be made using cells?
Q24. What are electromagnets?
Q25. How does a heating element work in an electric heater?
Q26. Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.
Q27. What is MCB and what is it used for?
Q28. An electrician is carrying out some repairs in your house. He wants to replace a fuse by a piece of wire. Would you agree? Give reasons for your response.
Q29. What are the reasons for excessive currents in the electrical circuits?
Q30. The following Fig. shows four cells fixed on a board. Draw lines to indicate how you will connect their terminals with wires to make a battery of four cells.