Q14 of 47 Page 406

Overloading in an electric circuit causes fire. Many people are unaware of this fact. Amit, an intelligent student told people of his building about overloading. He told them various precautions to avoid it questions:

(i) What harm does overloading in the circuit cause?


(ii) What values are shown by Amit?

(i) Overloading can lead to damage, poor performance and possible failure. There may be a risk of fire or damage to components. It can also lead to sparks, arcs or insulation failure. Current overload will cause things to heat up, and then possibly melt, set of fire, damage insulation or cause components to fail. Some components will be damaged by the excessive current without overheating

(ii) Amit is very caring and worried towards his society and people. He is also quite ware and intelligent. He uses his knowledge of science for helping society which is the sole purpose of education.


More from this chapter

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12

You are given the following current- time graphs from two different sources:


Now, answer the following questions:


(i) Name the type of current in two cases.


(ii) Identify any one source for each type of these currents.


(iii) What is the frequency of current in case (b) in India?


(iv) Use above graphs to write two differences between the current in two cases.

 13


(i) The figure shows a domestic electric circuit. Study this circuit carefully and list any three errors in the circuit and justify your answer.


(ii) Give one difference between the wires used in the element of an electric heater and in a fuse.


(iii) List two advantages of parallel connection over series connection.

 15

Raja had gone to his aunt’s home in a foreign country, where domestic electric supply is DC. An electrician working in her kitchen was trying to locate the electric wiring in a particular wall for some electrical work but failed to do so. Electrician, then suggested the breaking of substantial position of wall to Rajat’s aunt.

But Rajat told his aunt that he could locate the position of current carrying wires in the kitchen without any breakage. He brought a small device from market and within ten minutes, located the position of all current carrying wires on wall of his aunt got very happy from him.


Read the above passage and answer the following questions:


(i) Which device was purchased by Rajat?


(ii) What was noticed by Rajat when he moved this device slowly over the current carrying wires embedded kitchen?


(iii) What values are shown by Rajat in this episode?

 1

Which of the following figures shows the correct magnetic field lines?