- AA ferromagnetic material becomes paramagnetic.
- BA paramagnetic material becomes diamagnetic.
- CA ferromagnetic material becomes diamagnetic.
- DA paramagnetic material becomes ferromagnetic.
Explanation:
Curie Tempearture is the temperature at which certain materials lose their permanent magnetic properties, to be replaced by induced magnetism. In other words, it is the temperature above which a ferromagnetic material becomes paramagnetic.
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The most commonly used material for making transistor is
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(a) Copper |
(b) Silicon |
(c) Ebonite |
(d) Silver |
A lens of focal power 0.5 D is
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(a) A convex lens of focal length 0.5 m |
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(b) A concave lens of focal length 0.5 m |
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(c) A convex lens of focal length 2 m |
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(d) A concave lens of focal length 2 m |
A coil having n turns and resistance R W is connected with a galvanometer of resistance 4RΩ. This combination is moved in time t seconds from a magnetic field W1 weber to W2 weber. The induced current in the circuit is
|
(a) |
(b) |
(c) |
(d) |
Two wires have resistance of 2W and 4W connected to same voltage, ratio of heat dissipated at resistance is
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(a) 1 : 2 |
(b) 4 : 3 |
(c) 2 : 1 |
(d) 5 : 2 |
If 96500 coulombs of electricity liberates one gram equivalent of any substance, the time taken for a current of 0.15 amperes to deposite 20mg of copper from a solution of copper sulphate is (Chemical equivalent of copper = 32)
|
(a) 5 min 20 sec |
(b) 6 min 42 sec |
(c) 4 min 40 sec |
(d) 5 min 50 sec |
Mass of earth has been determined through
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(a) Use of Kepler's |
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(b) Sampling the density of earth's crust and using R |
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(c) Cavendish's determination of G and using R and 'g' at the surface |
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(d) Use of periods of satellites at different heights above earth's surface |
Match the List I with the List II from the combination shown. In the left side (List I) there are four different conditions and in the right side (List II), there are ratios of heat produced in each resistance for each condition :
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List I |
List II |
||
|
(I) |
Two wires of same resistance are connected in series and same current is passed through them |
(A) |
1 : 2 |
|
(II) |
Two wires of resistance R and 2R ohm are connected in series and same P.D. is applied across them |
(B) |
4 : 1 |
|
(III) |
Two wires of same resistance are connected in parallel and same current is flowing through them |
(C) |
1 : 1 |
|
(IV) |
Two wires of resistances in the ratio 1 : 2 are connected in parallel and same P.D. is applied across them |
(D) |
2 : 1 |
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(a) I – B; II – A; III – C; IV - D |
(b) I – C; II – D; III – C; IV - D |
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(c) I – B; II – D; III – A; IV - C |
(d) I – A; II – B; III – D; IV - C |
If
is 6563 Å, then wave length of second line for Balmer series will be
|
(a) |
(b) |
(c) |
(d) None of the above |