All India Pre-Medical / Pre-Dental Entrance Examination

CBSE Guess > AIPMT > AIPMT 2007 Screening > Physics

AIPMT 2007 Physics Screening

Q. 41. In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential V and then made to describe semicircular paths of radius R using a magnetic field B. If V and B are kept constant, the ratio will be proportional to

1. R
2. 1/R
3. 1/R²
4. R²

Sol . Radius of path Correct choice: (3)

Q. 42. If the nucleus 13 has a nuclear radius of about 3.6 fm, then Te
would have its radius approximately as

1. 4.8 fm
2. 6.0 fm
3. 9.6 fm
4. 12.0 fm

Sol. Correct choice: (2)

Q. 43. In radioactive decay process, the negatively charged emitted particles are

1. the electrons orbiting around the nucleus
2. the electrons present inside the nucleus
3. the electrons produced as a result of the decay of neutrons inside the nucleus
4. the electrons produced as a result of collisions between atoms

Sol . When neutron decays as given Correct choice: (3)

Q. 44. A nucleus has nucleus A X
Z has mass represented by M (A, Z). If M_p and M_n denote the mass of proton and neutron respectively and B.E the binding energy in Me V then

Sol. Correct choice: (3)

Q. 45. Two radioactive substances A and B have decay constants respectively. At t = 0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be after a time interval

Sol.

Correct choice: (1)

Q. 46. The total energy of electron in the ground state of hydrogen atom is –13.6 eV. The kinetic energy of an electron in the firstm excited state is

1. 1.7 eV
2. 3.4 eV
3. 6.8 eV
4. 13.6 eV

Sol. Total energy in 1st excited state Correct choice: (2)

Q. 47. In the energy band diagram of a material shown below, the open circles and filled circles denote holes and electrons respectively. The material is

1. an n-type semiconductor
2. a p-type semiconductor
3. an insulator
4. a metal

Sol. In diagram acceptor level is near valance band which will happen in p-type semiconductor. Correct choice: (2)

Q. 48. A common emitter amplifier has a voltage gain of 50, an input impedance of and an output impedance of . The power gain of the amplifier is

1. 100
2. 500
3. 1000
4. 1250

Sol. Correct choice: (4)

Q. 49. In the following circuit, the output Y for all possible inputs A and B is expressed by the truth table

Q. 50. For a cubic crystal structure which one of the following relations indicating the cell characteristics is correct?

Sol. the cubic system is the most symmetric out of all seven crystal systems. All edges for the unit cell are same i.e., a = b = c and all angles are right angles i.e., Correct choice: (1)