NCERT Solutions for Class 12 Physics Chapter 7 Alternating Current  7.1. A 100 Ω resistor is connected to a 220 V, 50 Hz ac supply. (a) What is the rms value of current in the circuit? (b) What is the net power consumed over a full cycle? Solution :  (a) $I_{rms} = \frac{v_{rms}}{R} = \frac{220}{100} = 2.20 A$ (b) $Net power = V_{rms} \times I_{rms} = 220 \times 2.20$ = 484 W 7.2 (a) The peak voltage of an ac supply is 300 V. What is the rms voltage? (b) The rms value of current in an ac circuit is 10 A. What is the peak current?  Solution:   (a) $V_{rms} = \frac{V_{0}}{\sqrt{2}} =\frac{300}{\sqrt{2}} = 212.1 V$ (b) $I_{rms} = \frac{I_{0}}{\sqrt{2}}$ $I_{0} = I_{rms} \sqrt{2} = 10 \sqrt{2} = 14.1A$ 7.3 A 44 mH inductor is connected to 220 V , 50 Hz ac supply. Determine the rms value of the current in the circuit. Solution:  Here , Reactance $X_{L} = 2 \pi\nu L = 2\pi \times 50 \times 44 \times 10^{-3}$ $\therefore I_{rms} = \frac{V_{rms}}{X_{L}} = \frac{220}{2\p...

Learn about the Second's Pendulum in Class 11 Physics Chapter 13 Oscillation with its definition, formula, derivation, length, frequency, numerical. Easy NCERT-based notes JEE NEET - Physics kund  Second's Pendulum A second's pendulum is a simple pendulum whose time period (T) is 2 seconds . Formula for Time Period \[ T = 2\pi \sqrt{\frac{L}{g}} \] Squaring both sides, \[ T^2 = \frac{4\pi^2L}{g} \] Therefore, the length of the pendulum is \[ L = \frac{T^2g}{4\pi^2} \] Calculation of Length For a second's pendulum, \(T = 2\;s\) \(g = 9.8\;m/s^2\) \[ L = \frac{(2)^2 \times 9.8}{4\pi^2} = \frac{39.2}{39.48} \approx 0.993\;m \approx 1\;m \] Hence, the length of a second's pendulum is \[ L \approx 1\;m = 100\;cm \] Frequency of Second's Pendulum Frequency is given by \[ ...

The Simple Pendulum is one of the simplest examples of Simple Harmonic Motion (SHM) . It consists of a small heavy bob suspended from a fixed support by a light, flexible and inextensible string. When the bob is displaced slightly from its equilibrium position and released, it oscillates to and fro in a vertical plane. For small angular displacements, the motion of the pendulum is simple harmonic. Definition of Simple Pendulum A simple pendulum is an ideal mechanical system consisting of a point mass (called the bob) suspended by a light, massless and inextensible string from a rigid support. The bob is free to oscillate in a vertical plane under the action of gravity. In practice, a true simple pendulum cannot be realized because the bob is not a perfect point mass and the string has a small mass. Therefore, a small metallic bob suspended by a light thread is considered a good approximation of a simple pendulum. Construction of a Simple Pendulum A rigid support is fixed a...

Energy in Simple Harmonic Motion (SHM) A particle executing Simple Harmonic Motion (SHM) possesses both Kinetic Energy (K.E.) and Potential Energy (P.E.) . During the motion, these two forms of energy continuously transform into each other. When one increases, the other decreases by the same amount. In the absence of non-conservative forces, the total mechanical energy remains constant . At the mean position , the particle has maximum velocity; therefore, its kinetic energy is maximum and potential energy is zero. At the extreme positions , the velocity becomes zero; hence kinetic energy is zero while potential energy becomes maximum. The total mechanical energy of a particle executing SHM is the sum of its kinetic and potential energies. $$E=K+U$$ E = Total Mechanical Energy K = Kinetic Energy U = Potential Energy Potential Energy in SHM Potential Energy is the energy possessed by a particle due to its position. In SHM, it is equal to the work done against th...

Learn Periodic Motion, Oscillatory Motion, and Vibratory Motion with complete Class 11 Physics notes. Understand definitions, characteristics, differences, examples, equilibrium position, restoring force, time period, frequency, FAQs, MCQs, true/false questions, fill in the blanks, and exam-oriented questions in one comprehensive guide. Suitable for NCERT, CBSE, State Boards, and competitive exams - Physicskund  Periodic Motion A motion that repeats itself after equal intervals of time is called Periodic Motion . The interval after which the motion repeats is known as the time period . In periodic motion, the body returns to the same position and state of motion after every fixed interval of time. Periodic motion does not necessarily involve motion along the same path or about a fixed point. It may be circular, rotational, linear, or oscillatory. Therefore, the existence of an equilibrium position is not compulsory for periodic motion. Characteristics of Periodic Motion ...

Surface Tension , Relation With Surface Tension and Surface Energy, Formula, Derivation, MCQs , FAQs class 11 physics chapter 9 Mechanical Properties of fluids  Surface Energy Define surface energy. Write its SI unit and dimensional formula. We know that the molecules on the liquid surface experience a net downward force. So, to bring a molecule from the interior of the liquid to the free surface, some work is required to be done against the intermolecular force of attraction. This work is stored as the potential energy of the molecule on the surface. The potential energy of surface molecules per unit area of the surface is called surface energy . $$ \text{Surface Energy}=\frac{\text{Potential Energy}}{\text{Area}} $$ Units of Surface Energy System of Unit Unit of Surface Energy CGS erg cm -2 SI J m -2 Dimensional Formula of Surface Energy Surface energy is defined as: $$ \text{Surface Energy}=\frac{\text{Potential Energy}}{\text{Area}} $$ The dim...