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An electromagnet does not attract a piece of iron. - Science

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प्रश्न

An electromagnet does not attract a piece of iron.

पर्याय

  • True

  • False

MCQ
चूक किंवा बरोबर
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उत्तर

This statement is False.

Explanation:

  • The working of an electromagnet is based on the magnetic effect of electric current.
  • When current passes through it, an electromagnet behaves as a magnet, attracting a piece of iron.
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पाठ 14: Electric Current and Its Effects - Exercises [पृष्ठ १७१]

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एनसीईआरटी Science [English] Class 7
पाठ 14 Electric Current and Its Effects
Exercises | Q 9.3 | पृष्ठ १७१

संबंधित प्रश्‍न

A coil is connected to a galvanometer. When the N-pole of magnet is pushed into the coil, the galvanometer deflected to the right. What deflection, if any, is observed when: 

the magnet is a rest in the coil? 


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.


(c) Considering the relationship in the first pair, complete the second paie :
AgCI : White :: CuI2 : ___________


(b) State whether the following statements are true or false:

(i) Magnetic poles exist in pairs.


Read the given passage and answer the following questions:

The home electrical connection consists of ‘live’, ‘neutral’ and ‘earth’ wires. The ‘live’ and the ‘neutral’ wires have potential difference of 220 V. The ‘earth’ is connected to ground. Due to a fault in the equipment or if the plastic coating on the ‘live’ and the ‘neutral’ wires gives a way the two wires come in contact with each other and a large current flows through it producing heat. If any inflammable material (such as wood, cloth, plastic, etc.) exists around that place it can catch fire. Therefore a fuse wire is used as a precautionary measure.

  1. Name the two wires having potential difference of 220 V.
  2. What is a short circuit?
  3. Write the function of a fuse.

A uniform magnetic field exists in the plane of paper pointing from left to right as shown in Figure. In the field an electron and a proton move as shown. The electron and the proton experience


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.


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


Sailors use ______ to find direction in order to navigate on the sea.


As shown in the diagram an aluminium rod 'AB' is suspended horizontally between the two poles of a strong horse shoe magnet in such a way that the axis of rod is horizontal and the direction of the magnetic field is vertically upward. The rod is connected in series with a battery and a key.

State giving reason:

  1. What is observed when a current is passed through the aluminium rod from end B to end A?
  2. What change is observed in a situation in which the axis of the rod 'AB' is moved and aligned parallel to the magnetic field and current is passed in the rod in the same direction?

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