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

Deuterium is the most common isotope of hydrogen. How many neutrons does it have?

To obtain P-type Si semiconductor, we need to dope pure Si  with(a) Aluminium(b) Phosphorous(c) Oxygen(d) Germanium

Point charges +4q, -q  and +4q  are kept on the x - axis at points x = 0, x = a  and x = 2a respectively, then(a) Only q is in stable equilibrium(b) None of the charges are in equilibrium(c) All the charges are in unstable equilibrium(d) All the charges are in stable equilibrium

A tank is filled with benzene to a height of 120 mm. The apparent depth of a needle lying at a bottom of the tank is measured by a microscope to be 80 mm.  The refractive index of benzene is(a) 1.5 (b) 2.5(c) 3.5(d) 4.5

n immersion heater is rated 836 watt. It should heat 1 litre of water from 10℃  to 40℃  in about(a) 200 sec(b) 150 sec(c) 836 sec(d) 418 sec

The refractive index of a certain glass is 1.5 for light whose wavelength in vacuum is 6000 Å. The wavelength of this light when it passes through glass is(a) 4000 Å (b) 6000 Å (c) 9000 Å (d) 15000 Å 

The wavefront of a distant source of unknown shape is approximately:

An electron microscope is superior to an optical microscope in(a) Having better resolving power  (b) Being easy to handle  (c) Low cost  (d) Quickness of observation 

Two point charges Q  and – 3Q are placed at some distance apart. If the electric field at the location of Q is E then at the locality of -3Q, it is(a) - E (b) E/3(c) -3E (d) -E/3