- AMagnetic needle
- BBar magnet
- CMagnetite
- DHorseshoe magnet
Explanation:
Pieces of naturally occurring iron ore, lodestone or magnetite had the property of attracting small pieces of iron. Hence, magnetite is a natural magnet. All natural magnets are permanent magnets, meaning they will never lose their magnetic power.
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One cannot see through fog because .......... :
Two identical thin rings each of radius R meters are coaxially placed at a distance R meters apart. If Q1 coulomb and Q2 coulomb are respectively the charges uniformly spread on the two rings, the work done in moving a charge qfrom the centre of one ring to that of other is
|
(a) Zero |
(b) |
(c) |
(d) |
A body has – 80 micro coulomb of charge. Number of additional electrons in it will be
|
(a) 8 |
(b) 80 |
(c) 5 |
(d) 1.28 |
A resistance of 4 and a wire of length 5 metres and resistance 5
are joined in series and connected to a cell of e.m.f. 10 V and internal resistance 1
. A parallel combination of two identical cells is balanced across 300 cm of the wire. The e.m.f. E of each cell is
|
(a) 1.5 V |
(b) 3.0 V |
(c) 0.67 V |
(d) 1.33 V |
Two voltameters, one of copper and another of silver, are joined in parallel. When a total charge q flows through the voltameters, equal amount of metals are deposited. If the electrochemical equivalents of copper and silver are
and
respectively the charge which flows through the silver voltameter is
|
(a) |
(b) |
(c) |
(d) |
Four capacitors are connected as shown in the figure. Their capacities are indicated in the figure. The effective capacitance between points x and y is (in μF)
|
(a) |
(b) |
(c) |
(d) 2 |
