- Aappropriate choice is not given
- Bcylindrical
- ✓spherical
- Dplane
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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 |
The tail of the comet is due to
|
(a) Vaporisation of water on the comet |
|
(b) Sublimation of vapour in the comet |
|
(c) Cooling of water in the comet |
|
(d) Vaporisation of heat in the comet |
Eight dipoles of charges of magnitude e are placed inside a cube. The total electric flux coming out of the cube will be
|
(a) |
(b) |
(c) |
(d) Zero |
Choke coil works on the principle of
|
(a) Transient current |
(b) Self induction |
(c) Mutual induction |
(d) Wattless current |

A wire of length 1 m is moving at a speed of 2ms–1 perpendicular to its length and a homogeneous magnetic field of 0.5 T. The ends of the wire are joined to a circuit of resistance 6 W. The rate at which work is being done to keep the wire moving at constant speed is
|
(a) |
(b) |
(c) |
(d) 1W |
A highly conducting ring of radius R is perpendicular to and concentric with the axis of a long solenoid as shown in fig. The ring has a narrow gap of width d in its circumference. The solenoid has cross sectional area A and a uniform internal field of magnitude B0. Now beginning at t = 0, the solenoid current is steadily increased to so that the field magnitude at any time t is given by B(t) = B0 + at where α > 0. Assuming that no charge can flow across the gap, the end of ring which has excess of positive charge and the magnitude of induced e.m.f. in the ring are respectively

|
(a) X, A𝛼 |
(b) X, pR2𝛼 |
(c) Y, 𝜋A2𝛼 |
(d) Y, pR2𝛼 |
In the nth orbit, the energy of an electron
for hydrogen atom. The energy required to take the electron from first orbit to second orbit will be
|
(a) 10.2 eV |
(b) 12.1 eV |
(c) 13.6 eV |
(d) 3.4 eV |
A particle has a mass 400 times than that of the electron and charge is double than that of a electron. It is accelerated by 5V of potential difference. Initially the particle was at rest, then its final kinetic energy will be
|
(a) 5 eV |
(b) 10 eV |
(c) 100 eV |
(d) 2000 eV |
If in the circuit shown below, the internal resistance of the battery is 1.5 W and VP and VQ are the potentials at P and Q respectively, what is the potential difference between the points P and Q

|
(a) Zero |
(b) 4 volts (VP > VQ) |
(c) 4 volts (VQ > VP) |
(d) 2.5 volts (VQ > VP) |