PHY101
Short Notes Final Term Exam
Q#1) Define Gauss’s Law?
Ans:
The total electric flux leaving a closed
surface is equal to the charge enclosed by the surface divided by ϵ0 . We can expressed in mathematics form
Q#2) Define electric potential?
Ans:
The electric potential is the energy of a
unit charge in an electric field. So in our MKS units the unit of potential is
1Joule/Coulombs=1Volt.Another useful unit is 1Electron Volt.
Q#3) Define 1Ev?
Ans:
One electron volt is defined as the
energy gained by an electron when it is accelerated through a potential
difference of 1 volt.
The formula for energy in terms of charge and potential difference
is E = QV. So 1 eV = (1.6 x 10^-19 coulombs)x(1 volt) = 1.6 x 10^-19
Joules.
Q#4) Given a system of charges, we can always compute the force - and
hence the potential - That arises from them. Here are some important general
statements:
a) Potentials are more positive in regions which have more positive
charge.
b) The electric potential is a scalar quantity (a scalar field,
actually).
c) The electric potential determines the force through F=− du/dr,
and hence the electric Field because F= qE.
d) The electric potential exists only because the electrostatic force is
conservative
Q#5) Define Capacitor?
Ans:
A capacitor is a passive electronic
component that stores energy in the form of an electrostatic field. In its
simplest form, a capacitor consists of two conducting plates separated by an
insulating material called the dielectric.
Q#6) Define Resistance?
Ans:
Resistance is directly
proportional to the voltage V and inversely proportional to the current
R=VI
Important:
When resistors are put in series with each other, the same current flows
through both. When current flows in a circuit work is don
Q#7) Define Kirchhoff’s Law
ANS:
The sum of the potential differences
encountered in moving around a Closed circuit is zero.
Q#8) Define Weber?
Ans:
The dimension of flux is
magnetic field x area, and the unit is called Weber.
Q#9) Define alternating current
Ans:
Alternating current (AC) is current
that flows first in one direction along a wire, and then in the reverse
direction.
Q#10) Define Emission?
Ans: Matter releases energy as light.
Q#11) Define Absorption?
Ans: Mater takes energy from light.
Q#12) Define Transmission?
Ans: Matter allows light to pass through it.
Q#13) Define Reflection?
Ans: Matter repels light in another direction.
Q#14) Explain why mercury rises in thermometer when is it put in the hot
water?
Ans:
It consists of a bulb containing mercury
which is then attached to a narrow glass tube. As temperature rises, the level
of mercury in the tube increases. This happens because the volume of mercury
slightly increases with temperature.
Q#15) Do all current-carrying conductors emit electromagnetic
waves?
Ans:
Yes all current carrying conductors emit electromagnetic waves, and these are at the right angle of the current passes through as right hand rule of Fleming's explains it.
The formula for energy in terms of charge and potential difference
is E = QV. So 1 eV = (1.6 x 10^-19 coulombs)x(1 volt) = 1.6 x 10^-19
Joules.
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