A battery is used to charge a parallel plate capacitor till the potential difference between the plates becomes equal to the electromotive force of the battery. The ratio of the energy stored in the capacitor and the work done by the battery will be
(1) 1 (2) 2 (3) 1/4 (4) 1/2
A current I flows along the length of an infinitely long, straight, thin walled pipe. Then
(1) the magnetic field is zero only on the axis of the pipe
(2) the magnetic field is different at different points inside the pipe
(3) the magnetic field at any point inside the pipe is zero
(4) the magnetic field at all points inside the pipe is the same, but not zero
In gamma ray emission from a nucleus
(1) both the neutron number and the proton number change
(2) there is no change in the proton number and the neutron number.
(3) only the neutron number changes
(4) only the proton number changes
The half-life period of a radio-active element X is same as the mean life time of another radioactive element Y. Initially they have the same number of atoms. Then
(1) X will decay faster than Y
(2) Y will decay faster than X
(3) X and Y have same decay rate initially
(4) X and Y decay at same rate always.
Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the following statements is most appropriate?
(1) The number of free conduction electrons is significant in C but small in Si and Ge.
(2) The number of free conduction electrons is negligible small in all the three.
(3) The number of free electrons for conduction is significant in all the three.
(4) The number of free electrons for conduction is significant only in Si and Ge but small in C.