Semiconductor Electronics : Materials Devices and Simple Circuits — Physics STD 12 Science — Question

Two electric charges 12μC and -6 μC  are placed 20 cm apart in air. There will be a point P on the line joining these charges and outside the region between them, at which the electric potential is zero. The distance of P from -6 μC  charge is (a) 0.10 m(b) 0.15 m(c) 0.20 m(d) 0.25 m

Copper has face centered cubic (fcc) lattice with interatomic spacing equal to 2.54Å. The value of the lattice constant for this lattice is (a) 1.27 Å(b) 5.08 Å(c) 2.54 Å   (d) 3.59 Å

12 cells each having same emf are connected in series with some cells wrongly connected. The arrangement is connected in series with an ammeter and two cells which are in series. Current is 3 A when cells and battery aid each other and is 2 A when cells and battery oppose each other. The number of cells wrongly connected is(a) 4 (b) 1(c) 3  (d) 2

A hydrogen atom (ionisation potential 13.6 eV) makes a transition from third excited state to first excited state. The energy of the photon emitted in the process is(a) 1.89 eV(b) 2.55 eV(c) 12.09 eV(d) 12.75 eV

The wavelength of light visible to eye is of the order of:

27 small drops of water with equal radius and equal charge comprised to form one big drop. The ratio of capacitance of a big drop and capacitance of a small drop will be:

Consider a collision between an oxygen molecule and a hydrogen molecule in a mixture of oxygen and hydrogen kept at room temperature. Which of the following are pcssible?

1. The kinetic energies of both the molecules increase.
2. The kinetic energies of both the molecules decrease.
3. The Kinetic energy of the oxygen molecule increases and that of the hydrogen molecule decreases.
4. The kinetic energy of the hydrogen molecule increases and that of the oxygen molecule decreases.

Let V and E denote the gravitational potential and gravitational field at a point. It is possible to have:

1. V = 0 and E = 0
2. V = 0 and E ≠ 0
3. V ≠ 0 and E = 0
4. V ≠ 0 and E ≠ 0

A conducting loop is kept in a uniform magnetic field such that its plane is perpendicular to the magnetic field. Induced emf will be generated in the loop if: