NCERT Example 8.2
Coulomb’s law for electrostatic force between two point charges and Newton’s law for gravitational force between two stationary point masses, both have inverse-square dependence on the distance between the charges and masses respectively. (a) Compare the strength of these forces by determining the ratio of their magnitudes (i) for an electron and a proton and (ii) for two protons. (b) Estimate the accelerations of electron and proton due to the electrical force of their mutual attraction when they are 1 Å (= $10^{-10}$ m) apart? ($m_p$ = 1.67 × $10^{–27}$ kg, $m_e$ = 9.11 × $10^{–31}$ kg)
NCERT Example 1.3
Coulomb’s law for electrostatic force between two point charges and
Newton’s law for gravitational force between two stationary point
masses, both have inverse-square dependence on the distance between
the charges and masses respectively. (a) Compare the strength of
these forces by determining the ratio of their magnitudes (i) for
an electron and a proton and (ii) for two protons. (b) Estimate
the accelerations of electron and proton due to the electrical force
of their mutual attraction when they are 1 Å (= $10^{-10}$ m) apart?
($m_p$ = 1.67 × $10^{–27}$ kg, $m_e$ = 9.11 × $10^{–31}$ kg)
If $10^9$ electrons move out of a body to another body every second, how much time is required to get a total charge of 1 C on the other body?
NCERT Example 1.1 If $10^9$ electrons move out of a body to another body every second, how much time is required to get a total charge of 1 C on the other body?
How much positive and negative charge is there in a cup of water?
NCERT Example 1.2 How much positive and negative charge is there in a cup of water?
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Physics is a multi dimensional subject and has to be studied from many different aspects. The purpose of this website is to provide students of class 11, 12 and entrance exam preparers with high quality study materials and useful resources.
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NEET Past Year Questions Practice
11P03 Motion in a Plane 2D
Circular Motion
Maximum Safe speed while taking a turn in Level Road and Banked Road.
To simulate car accidents, auto manufacturers study the collisions of moving cars with mounted springs of different spring constants. Consider a typical simulation with a car of mass 1000 kg moving with a speed 18.0 km/h on a smooth road and colliding with a horizontally mounted spring of spring constant 5.25 × 10^3 N m–1. What is the maximum compression of the spring ? Example 5.9 Consider Example 5.8 taking the coefficient of friction, µ, to be 0.5 and calculate the maximum compression of the spring.
Example 5.8 To simulate car accidents, auto manufacturers study the collisions of moving cars with mounted springs of different spring constants. Consider a typical simulation with a car of mass 1000 kg moving with a speed 18.0 km/h on a smooth road and colliding with a horizontally mounted spring of spring constant $5.25\times 10^3 Nm^{-1}$ . What is the maximum compression of the spring ? [NCERT Class 11 Example 5.8]
Example 5.9 Consider Example 5.8 taking
the coefficient of friction, µ, to be 0.5 and
calculate the maximum compression of the
spring. [NCERT Class 11 Example 5.9]
$5.25\times 10^3 Nm^{-1}$ corrected as $6.25\times 10^3 Nm^{-1}$
Three concentric spherical shells have radii a, b and c (a < b < c) and have surface charge densities σ,−σ and σ respectively. If VA, VB and VC denotes the potentials of the three shells, then for c = a + b, we have [NEET 2009]
Three concentric spherical shells have radii a, b and c (a < b <
c) and have surface charge densities σ,−σ and σ respectively. If VA, VB
and VC denotes the potentials of the three shells, then for c = a + b,
we have [NEET 2009]
a) $V_C=V_B\neq V_A$
b) $V_C\neq V_B\neq V_A$
c) $V_C=V_B=V_A$
d) $V_C=V_A\neq V_B$
Concept: Use Van de graph principles. In concentric spheres, the
voltage due to the charges on the surface and the voltage due to the
inner spheres and outer spheres should be added. $V_{inside\hspace{2mm}sphere}= V_{at\hspace{2mm}surface\hspace{2mm}of\hspace{2mm}sphere}$
\[V_A=\frac{1}{4\pi\epsilon_o}\frac{q_A}{r_A}-\frac{1}{4\pi\epsilon_o}\frac{q_B}{r_B}+\frac{1}{4\pi\epsilon_o}\frac{q_C}{r_C}\]
\[=K\frac{\sigma 4\pi a^2}{a}-K\frac{\sigma 4\pi b^2}{b}+K\frac{\sigma 4\pi c^2}{c}\]
\[=K\sigma 4\pi \hspace{2mm}(a-b+c)\]
\[=K\sigma 4\pi \hspace{2mm}(a-b+a+b)\]
\[=K \sigma 4\pi \hspace{2mm} (2a) \]
A man of 50 kg mass is standing in a gravity free space at a height of 10 m above the floor. He throws a stone of 0.5 kg mass downwards with a speed of 2 m/s. When the stone reaches the floor the distance of the man above the floor will be
A man of 50 kg mass is standing in a gravity free space at a height of 10 m above the floor. He throws a stone of 0.5 kg mass downwards with a speed of 2 m/s. When the stone reaches the floor the distance of the man above the floor will be
A) 9.9 m B) 10.1 m C) 10 m D) 20 m
Concepts: Conservation of Linear momentum. Similar to the recoiling of gun. When the man pushes the stone downward the man will get pushed upward. Since there is no external force acting on the system, conservation of linear momentum is valid and center of mass of the whole system remains in the same location.
12P01 Electric Charges and Fields
Step-by-step
Step 1: Theory and Concepts
Step 2: Numerical Practice
NCERT Examples, NCERT Exercises with solutions
Step 3: Numerical Practice
Chapterwise CBSE Past papers (Any one of them- Arihant, MTG, XAM Idea etc.)
Step 4: Numerical Practice
Step 5: Numerical Practice
NEET past year Questions, Solutions
JEE Main past year Questions, Solutions
Two charges and Forces between them.
Plot F vs. r graph to see the shape of the graph.
How to solve Numerical problem in physics?
How
to solve Numerical problem in physics?
“Start walking. The path will become clearer”
·
Nature
is written in the language of Mathematics. Drawing is the language of Engineers
and Scientists.
·
Read
the question line by line converting it into a simple cartoon diagram or a
mathematical expression. Mark the numerical values in appropriate places in the
diagram or with the mathematical notations.
Charged Particle in a Uniform Electric Field. Calculate the vertical distance from the center line from where the particle will exit the parallel plate region.
Charged Particle in a Uniform Electric Field
Calculate the vertical distance from the center line
from where the particle will exit the parallel plate region.
One face of a rectangular glass plate 6 cm thick is silvered. An object held 8 cm in front of the first face forms an image 12 cm behind the silvered face. The refractive index of the glass is
One face of a rectangular glass plate 6 cm thick is silvered. An object held 8 cm in front of the first face forms an image 12 cm behind the silvered face. The refractive index of the glass is
A) 0.4 B) 0.8 C) 1.2 D) 1.6
12P02 Electric Potential and Capacitance
Understand how much distance I have to move to cause a voltage difference of 1 V
a) Far away from the source charge b) Very close to the source charge.
Connect that finding with Conservative Force / Field concepts
Equipotential Lines for two charges separated by a distance
$E= - \frac{dV}{dr} \; \; F = -\frac{dU}{dr}$
a) oppositely charged b) same charged
Capacitor Basics
Change the battery voltage and see what happens to
the charge and the voltage in the capacitor, Q = C V
Change the area and gap between the plates and see what happens
to the Capacitance value, C = epsilon_o A / d
12P07 Alternating Current
Virtual Oscilloscope to try different waveforms and also to input your own voice.
From the seconds/div calculate the frequency of the wave and double check the value.
What is the formula or relation between time period, frequency, angular frequency?
In a double slit experiment two coherent beams have slightly different intensities I and $\delta I$. Show that the resultant intensity at the maxima is nearly 4I, while that at the minima is $(\delta I)^2/4I$
In a double slit experiment two coherent beams have slightly different
intensities I and $\delta I$. Such that I >>$\delta I$. Show that the resultant intensity at the maxima is nearly 4I, while that
at the minima is $(\delta I)^2/4I$
Courtesy:ophysics.com
For Intensity at Maxima,
\[ I=I_1+I_2+2\sqrt{I_1 I_2}\cos\phi \]
\[I_{max}=I+\left(I+\delta I\right)+2\sqrt{I(I+\delta I)}\cos 0\]
\[=2I+\delta I+2I\left(1+\frac{\delta
I}{I}\right)^{\frac{1}{2}}\]
\[=2I+\delta I+2I\left[1+\frac{1}{2}\frac{\delta
I}{I}+\frac{\frac{1}{2}.\frac{-1}{2}}{2}\left(\frac{\delta
I}{I}\right)^2\right]\]
Using Binomial theorem, ignoring the higher order terms,
$(\frac{\delta I}{I})^{2}$
\[=4I+2\hspace{2mm}\delta I\]
\[\approx4I\]
FAQs by parents for Physics Class
"Teacher does not teach.Student learns.Teacher just helps in the process of learning."
Frequently asked questions for Physics Class
1) Sir, we heard you have stopped taking class. Are you by any chance taking classes?
Due to some throat pain issues, I took a break from classes from March 2024 to Sep 2024. Even now beyond 45 min, I am not able to speak comfortably, especially physics being a subject where one has to speak and explain a lot. So I am teaching few students coming to my home.
Pure Si at 500 K has equal no. of electron (n_e) and hole (n_h) concentrations of 1.5 ×10^16 m^-3. Doping by Indium increases n_h to 4.5 ×10^22 m^-3. Find the no. of electrons in the doped semiconductor and identify if it is p-type or n-type.
NEET PYQ, 12P14 Semiconductor Materials and Devices, p-type n-type semiconductor
12P14 Semiconductor Study Notes
Crystal Lattice and Logic Gates Study Notes -- PDF Notes
Interaction with 3D Models for Crystal Lattice SCC BCC FCC
Quantity of water or liquid flowing out of a tank through a hole orifice at the bottom of the tank. Mathematical Modelling and Experimental Results.
Quantity of water or liquid flowing out of a tank through a hole orifice at the bottom of the tank. Mathematical Modelling and Experimental Results.
Application of Integration methods to model quantities that are changing continuously in a non-linear fashion with respect to time.
This work was started as a way to illustrate the power of calculus in mathematical modelling to class 11 and 12 students, when we deal with quantities that are not changing linearly with respect to time or other variable. However the integration methods look slightly complicated and may be suitable only for college level students and fluid mechanics students.
Mathematical Model PDF File
Excel Calculations and Graphs Excel File
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