The balance point for this resistance is at a distance ${{l}_{1}}=58.3cm$. RD Sharma Class 12 Solutions; RD Sharma Class 11 Solutions Free PDF Download; Wheatstone Bridge: 3.15: Meter Bridge: 3.16: Potentiometer: NCERT Solutions CBSE Sample Papers Physics Class 12 Physics. 7. Conductivity. These Physics Chapter 2 Class 12 notes are going to be one of the best supplementary study materials besides a students textbooks. Question 25. The plot of the variation of potential difference A across a combination of three identical cells in series, versus current is shown along the question. (a) State the working principle of a potentiometer with help of a circuit diagram, explain how the internal resistance of a cell is determined. Mathematically, it is given by, $\Rightarrow \left( {{T}_{2}}-{{T}_{1}} \right)=\frac{{{R}_{2}}-{{R}_{1}}}{{{R}_{1}}\alpha }$, $\Rightarrow \left( {{T}_{2}}-27 \right)=\frac{82.14-71.87}{71.87\times 1.70\times {{10}^{-4}}}$, $\Rightarrow {{T}_{2}}={{867.5}^{\circ }}C$. Wideband Sigma Delta PLL Modulator. Derive an expression for the voltage across R when the sliding contact is in the middle of potentiometer wire. Charge on an electron = e (Comptt. Use the plot to find the charge flowing in 10s through the wire. Using equation (v) we can find internal resistance of the cell. Answer: Question 42. Physics Class 12 Syllabus. Using Kirchoffs first law at junction E, we get (Comptt. On replacing this cell and using a cell of unknown emf, the balance point shifts to 80 cm. (iii) The ratio of the maximum to the minimum resistance would be, $\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{nR}{R/n}={{n}^{2}}$. Thus, its resistivity can be considered nearly independent with an increase in temperature. Answer: Question 90. All India 2015) (i) Drift velocity. Thus, there would be large percentage errors in measurements. It is known that, resistance is related with the resistivity as: $\Rightarrow \rho =\frac{5\times 6.0\times {{10}^{-7}}}{15}$, $\Rightarrow \rho =2\times {{10}^{-7}}{{m}^{2}}$. The digital television transition, also called the digital switchover (DSO), the analogue switch/sign-off (ASO), the digital migration, or the analogue shutdown, is the process in which older analogue television broadcasting technology is converted to and replaced by digital television.Conducted by individual nations on different schedules, this primarily involves the (ii) For circuit on the right side Wheatstone bridge can also be used for measuring strain and pressure. Distinguish between emf () and terminal voltage (V) of a cell having internal resistance r. Draw a plot showing the variation of terminal voltage (V) vs the current (I) drawn from the cell. Higher Semiconductors Notes [pdf 5MB] 8. Factors affecting internal resistance of a cell : (a) Internal resistance of a cell depends upon : Ans: When $X$ and $Y$are interchanged, then ${{l}_{1}}$ and $100-{{l}_{1}}$ also get interchanged. = (3 1.5)2 4 W In a way, a cylindrical capacitor houses a parallel plate capacitor, but a rolled-up insulating dielectric layer is present in the middle. Wire wrap. These solutions are as per the updated CBSE guidelines for Class 12. Reading of milliammeter = 0.064 A, Question 44. Now, if we couldnt find a balance point with the given cell of emf $\varepsilon $, then the potential drop across $R$ and $X$ is lessened by putting a resistance in series with it. A voltage V is supplied to the potentiometer. In the electric network shown in the figure, use Kirchhoffs rules to calculate the power consumed by the resistance R = 4 . Some other examples are - Electrostatic Painting, Smoke Precipitators and Electrostatic Air Cleaning. Then, total number of free electrons in the conductor A battery of emf E and internal resistance r when connected across an external resistance of 12 ft, produces a current of 0.5 A. Working of Meter Bridge : Metre Bridge is special case of Wheatstone Bridge Answer: a) In a metre bridge the balance point is found to be at 39.5 cm from the end A, when the resistor Y is of $12.5\Omega $ . = (I1 + I2)2 R Answer: Redistribution of charge between two capacitors . Question 11. If r is the resistance per cm length of wire AC and l cm is the length of wire AB, then length of wire BC will be (100 l) cm Explain, with reason how the mobility of electrons in a conductor changes when the potential difference applied is doubled, keeping the temperature of the conductor constant. Temperature coefficient of resistance of nichrome averaged over the temperature range involved is $1.70\times {{10}^{-4}}^{\circ }{{C}^{-1}}$ . Find the resistance, in terms of R1 and R2, required to be connected to convert it into a voltmeter that can read upto 2V. So, we have created awesome list of formulas of physics. It is difficult to conduct experiments using only theories without the ability to measure. Answer: In the absence of electric field the electrons motion is random and the net velocity is zero. (Delhi 2009) (Comptt. (All India 2014) Clearly, the temperature coefficient of silver is ${{0.0039}^{\circ }}{{C}^{-1}}$. Clearly, the value of unknown emf is $1.247V$. A conductor of length L is connected to a dc source of emf e. If this conductor is replaced by another conductor of same material and same area of cross-section but of length 3L, how will the drift velocity change? (a) Potentiometer principle : When a constant current flows through a wire of uniform cross sectional area, the potential difference, across any length, is directly proportional to the length. More Free Study Material for Electrostatic Potential and Capacitance, 6. Justify your answer. (Comptt. It is difficult to conduct experiments using only theories without the ability to measure. Let's also learn more about light with ray optics and wave optics. All questions given in the exercise are solved here. Potentiometer-principle and applications to measure potential difference and for comparing emf of two cells; measurement of internal resistance of a Where can I download Physics NCERT Solutions for Class 12 Chapter 3 PDF? Also, the internal resistance of the cell is $r = 380\Omega$. Hence the net charge crossing any cross section in a unit time is zero. Answer: Question 102. Total emf of three cells in series = P.D corresponding to zero current = 6V MCQs in all electrical engineering subjects including analog and digital communications, control systems, power electronics, electric circuits, electric machines and NCERT Solutions For Class 11 Physics; NCERT Solutions For Class 11 Chemistry; Wheatstone Bridge Calculator: Work Calculator: Youngs Modulus Calculator: Zener Diode Calculator: RC/IC Circuit Frequency Variation calculator: Question 116. Hence it is not taken into consideration in the bridge formula. Similarly mass of the copper wire is given by: $\Rightarrow {{m}_{2}}={{A}_{2}}{{l}_{2}}\times {{d}_{2}}={{A}_{2}}{{l}_{2}}{{d}_{2}}$ (4). Electric Charge. Ans: In the above question it is provided that: ${{R}_{1}}=1\Omega ,{{R}_{2}}=2\Omega ,{{R}_{3}}=3\Omega $. (a) Deduce the relation between current I flowing through a conductor and drift velocity \(\overrightarrow{\mathbf{v}}_{d}\) of the electrons. Explain. These solutions can be a student's best study buddy as they help in providing the best guidance and make learning fun. To resolve this issue, Arkwright built housing for the workers nearby, becoming one of the first manufacturers to do so. Wheatstone Bridge-based circuit . We also explore closely related physics topics such as the Schrodinger Wave Equation, Biot Savart Law, and the Heisenberg Uncertainty Principle. The dotted curve shows how the random motion of the same electron gets modified when an electric field is applied. Now these resistances rCD and rEF are in series, Question 134. One leg includes the component of unknown resistance. Important Questions on Current Electricity of CBSE Class 12 Physics Chapter 3 can be accessed here. Thus this equation relating to the four resistors is called the balance condition for the galvanometer to give zero or null deflection. E = \(\frac{V}{l}\) Ans: All conducting elements need not satisfy Ohms law. Question 14. Describe briefly, with the help of a circuit diagram, how a potentiometer is used to determine the internal resistance of a cell. Positive charge. Resistance of the resistor $R$ is $8.5\Omega $. Figure shows two circuits each having a galvanometer and a battery of 3 V. Clearly, the internal resistance of the cell is $1.68\Omega$ . The electric field E set up inside the conductor is given by In the figure a long uniform potentiometer wire AB is having a constant potential gradient along its length. The effective resistance would be minimum when resistors are connected parallelly. The temperature T1 is lower. AP1 = l1 Which Topics are Covered in Current Electricity? Sir Charles Wheatstone / w i t s t n / FRS FRSE DCL LLD (6 February 1802 19 October 1875), was an English scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope (a device for displaying three-dimensional images), and the Playfair cipher (an encryption technique). The total resistance of a series combination of resistors is the algebraic sum of individual resistances. It employs UHF radio waves in the ISM bands, from 2.402 GHz to 2.48 GHz. NCERT Solutions For Class 12 Physics; NCERT Solutions For Class 12 Chemistry; NCERT Solutions For Class 12 Biology; NCERT Solutions For Class 12 Maths A meter bridge also called a slide wire bridge is an instrument that works on the principle of a Wheatstone bridge. Nichrome wire gets heated up more because of higher resistivity of nichrome. All India 2012) The reading on a high resistance voltmeter, when a cell is connected across it, is 2.0 V. i.e., when there is no current flowing in the circuit. (ii) If the galvanometer and battery are interchanged at the balance position, how will the balance point get affected? Wheatstone bridge is a very sensitive device. Answer: Limitations of Wheatstone Bridge. (Comptt. For instance, a vacuum diode semiconductor is a conductor which does not follow Ohms law. Per visualizzare le finalit per le quali ritengono di avere un interesse legittimo o per opporsi a questo trattamento dei dati, utilizzare il link della lista dei fronitori qui sotto. The resistance S should not be very small. Class 12 Physics NCERT Solutions: Download NCERT Solutions for Class 12 Physics solved by master teachers. (Comptt. Answer: Question 47. Make notes as you go through the chapters.
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