Two infinitely long parallel conducting plates having surface charge densities +σ and -σ respectively, are separated by a small distance. The medium between the plates is vacuum. If 
is the dielectric permittivity of vacuum, then the electric field in the region between the plates is
|
(a) 0 volts/meter |
(b) |
(c) |
(d) |
(c) 
volts/meter
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A wire carrying current I and other carrying 2I in the same direction produces a magnetic field B at the mid point. What will be the field when 2I wire is switched off
|
(a) B / 2 |
(b) 2B |
(c) B |
(d) 4B |
A wire carrying current i is shaped as shown. Section AB is a quarter circle of radius r. The magnetic field is directed
|
(a) At an angle π/4 to the plane of the paper |
|
(b) Perpendicular to the plane of the paper and directed in to the paper |
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(c) Along the bisector of the angle ACB towards AB |
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(d) Along the bisector of the angle ACB away from AB |
If in Rutherford’s experiment, the number of particles scattered at 90° angle are 28 per min, then number of scattered particles at an angle 60° and 120° will be
|
(a) 112/min, 12.5/min |
(b) 100/min, 200/min |
(c) 50/min, 12.5/min |
(d) 117/min, 25/min |
A 50 mH coil carries a current of 2 ampere. The energy stored in joules is
|
(a) 1 |
(b) 0.1 |
(c) 0.05 |
(d) 0.5 |
A nucleus of an element 
emits an a-particle first, a b-particle next and then a gamma photon. The final nucleus formed has an atomic number
|
(a) 200 |
(b) 199 |
(c) 83 |
(d) 198 |
Which of the following statements is true for an N-type semi-conductor
|
(a) The donor level lies closely below the bottom of the conduction band |
|
(b) The donor level lies closely above the top of the valence band |
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(c) The donor level lies at the halfway mark of the forbidden energy gap |
|
(d) None of above |
