हिंदी

Paheli does not have a night lamp in her room. She covered the bulb of her room with a towel in the night to get dim light. Has she taken the right step? Give one reason to justify your answer.

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प्रश्न

Paheli does not have a night lamp in her room. She covered the bulb of her room with a towel at the night to get dim light. Has she taken the right step? Give one reason to justify your answer.

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उत्तर

No, the towel may burn due to the heat produced by the bulb. Besides, it will also result in the wastage of electric energy. She could have used a lamp shade.

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अध्याय 14: Electric Current and Its Effects - VERY SHORT ANSWER QUESTIONS [पृष्ठ ७७]

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एनसीईआरटी एक्झांप्लर Science [English] Class 7
अध्याय 14 Electric Current and Its Effects
VERY SHORT ANSWER QUESTIONS | Q 10. | पृष्ठ ७७

संबंधित प्रश्न

An electric bell has an electromagnet. 


Fill in the following blank with suitable words: 

The magnetic effect of a coil can be increased by increasing the number of ........... increasing the ........... or inserting an ........... core.


If the direction of electric current in a solenoid when viewed from a particular end is anticlockwise, then this end of solenoid will be:

(a) west pole
(b) south pole
(c) north pole
(d) east pole


The direction of current flowing in the coil of an electromagnet at its two ends X and Y are as shown below:  

  

 What is the polarity of end X?

What is the polarity of end Y?   

Name and state the rule which you have used to determine the polarities. 


In the Activity shown below, how do we think the displacement of rod AB will be affected if

  1. current in rod AB is increased
  2. a stronger horse-shoe magnet is used
  3. length of the rod AB is increased?
  • Take a small aluminium rod AB (of about 5 cm). Using two connecting wires suspend it horizontally from a stand, as shown in Fig.
  • Place a strong horse-shoe magnet in such a way that the rod lies between the two poles with the magnetic field directed upwards. For this put the north pole of the magnet vertically below and south pole vertically above the aluminium rod (Fig.).
  • Connect the aluminium rod in series with a battery, a key and a rheostat.
  • Now pass a current through the aluminium rod from end B to end A.
  • What do you observe? It is observed that the rod is displaced towards the left. You will notice that the rod gets displaced.
  • Reverse the direction of current flowing through the rod and observe the direction of its displacement. It is now towards the right.
  • Why does the rod get displaced?


A current-carrying rod, AB, experiences a force perpendicular to its length and the magnetic field. Support for the magnet is not shown here, for simplicity.


What is the function of a split ring in an electric motor?


Name any two appliances which works on the phenomenon of magnetic effect of electric current.


Draw a neat labelled diagram to show the magnetic effect of electric current.


Why do we cover plug pin holes which are within the reach of children with cellotape or a plastic cover when not in use?


Using an electromagnet, you can make a working model of a railway signal as shown in figure.


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