Solution:
Key concept: The phenomenon of electromagnetic induction is used in this problem. Whenever the number of magnetic lines of force (magnetic flux) passing through a circuit changes (or a moving conductor cuts the magnetic flux) an emf is produced in the circuit (or emf induces across the ends of the conductor) is called induced emf. The induced emf persists only as long as there is a change or cutting of flux.
When cylindrical bar magnet is rotated about its axis, no change in flux linked with the circuit takes place, consequently no emf induces and hence, no current flows through the ammeter A.
Hence the ammeter shows no deflection.
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One junction of a certain thermoelectric couple is at a fixed temperature 
and the other junction is at temperature T. The thermo electromotive force for this is expressed by E = K(
] . At temperature 
the thermoelectric power is
|
(a) |
(b) |
(c) |
(d) |
If the radioactive decay constant of radium is 1.07 
per year, then its half life period is approximately equal to
|
(a) 8,900 years |
(b) 7,000 years |
(c) 6,476 years |
(d) 2,520 years |
A signal emitted by an antenna from a certain point can be received at another point of the surface in the form of
|
(a) Sky wave |
(b) Ground wave |
(c) Sea wave |
(d) Both (a) and (b) |
The resistance of the series combination of two resistance is S. When they are joined in parallel the total resistance is P. If S = nP, then the minimum possible value of n is
|
(a) 4 |
(b) 3 |
(c) 2 |
(d) 1 |
The potential energy of a particle of mass m is given by
U(x) = 
l1 and l2 are the de-Broglie wavelengths of the particle, when 0 £ x £ 1 and x > 1 respectively. If the total energy of particle is 2E0, the ratio 
will be
|
(a) 2 |
(b) 1 |
(c) |
(d) |
