In doping an intrinsic semiconductor to produce a p-type semiconductor,
the semiconductor is heated up
a donor element is added
an acceptor element is added
the semiconductor is conducted to a battery
Correct answer is C
If the dominant impurity atoms are ACCEPTOR type in the semiconductor, it will have a majority of holes over the electrons [p-type]
One major reason why electrical appliances in homes are normally earthed is that the-----------
person touching the appliance is safe from electric shock
appliances are maintained at a higher p.d. than the earth
appliances are maintained at a lower p.d. than the earth
appliances are maintained at the same p.d. with that of the earth
Correct answer is A
Earthing of an electrical appliance meant the outer metallic case of appliance is connected with earth, wire which is welded to the end of a copper rod and it is burned in the ground. It save the appliance during short-circuiting by passing Excessive current to earth
A lamp is rated 240 V, 60 W. Determine the resistance of the lamp when lit?
120\(\Omega\)
240\(\Omega\)
540\(\Omega\)
960\(\Omega\)
Correct answer is D
P = 60w, V = 240v, R = ?
P = \(\frac{V^2}{R}\)
: 60 = \(\frac{240^2}{R}\)
→ R * 60 = 57,600
R = \(\frac{57,600}{60}\)
R = 960\(\Omega\)
In a series R-L-C circuit at resonance, impedance is----
maximum
minimum
capacitive
inductive
Correct answer is A
Since the current flowing through a parallel resonance circuit is the product of voltage divided by impedance, at resonance the impedance, Z is at its maximum value.
(Z=R )
The speed of fast-moving neutrons in a nuclear reactor can be reduced by using?
graphite rods
concrete shield
iron rods
boron rods
Correct answer is A
Moderation is the process of the reduction of the initial high speed (high kinetic energy) of the free neutron.
Since energy is conserved, this reduction of the neutron speed takes place by transfer of energy to a material called a moderator.
There are several different types of moderating materials, and each have places where they are used more effectively.
Typically-used moderator materials include heavy water, light water, and graphite.