Physics 12th Important Question Bank PDF

## YASHASHREE ACADEMY ### IMPORTANT QUESTION BANK – PHYSICS (12th) **1 Mark questions** i) What is the formula for the maximum power rating of a Zener diode? ii) Calculate the minimum pressure required to force the blood from the heart to the top of the head (vertical distance = 50 cm). Assume the...

## YASHASHREE ACADEMY ### IMPORTANT QUESTION BANK – PHYSICS (12th) **1 Mark questions** i) What is the formula for the maximum power rating of a Zener diode? ii) Calculate the minimum pressure required to force the blood from the heart to the top of the head (vertical distance = 50 cm). Assume the density of blood to be 1.04 g cm-3. Friction is to be neglected. iii) What are magnetic lines of force? iv) An electron is accelerated through a potential difference of 100 volt. Calculate de-Brogliewavelength in nm. v) Define thermodynamic process. vi) State relation for magnetic field produced by current I in a coil of radius R having N turns at the centre. vii) In a Wheatstone's metrebridge experiment, the null point is obtained in middle one third portion of wire. Why is it recommended? viii) Define: binding energy. ix) What is an AC generator? x) A straight wire carries a current of 5 A. Calculate the magnitude of magnetic induction at a point 10 cm away from the conducting wire. (μ0 = 4π × 10–7 Wb/A m) xi) Define admittance. State its SI unit. xii) In which of the following cases, will the work done be more? **2 Marks Questions** - Explain the term gauge pressure. - What is interference? Give its examples. - Show that the end correction of a pipe closed at one end is given by e = (m1/12) - A gas in a cylinder is at pressure 500 N/m². If the masses of all the molecules are made one fifth of their original value and their speeds are doubled, then find the resultant pressure. - When 108 electrons are transferred from one conductor to another, a potential difference of 10 V appears between the conductors. Find the capacitance between the two conductors. - State the applications of Wheatstone bridge. - Can you explain why two or more resistors connected in series and parallel have different effective resistances? - State the necessary modifications needed to convert a moving coil galvanometer into a voltmeter. - Two magnets with the same dimensions and mass, but of magnetic moments µ₁ = 100 Am² and µ2 = 50 Am² are jointly suspended in the earth's magnetic field so as to perform angular oscillations in a horizontal plane. When their like poles are joined together, the period of their - Mention some applications of photocell. - Mention some of the applications of Zener diode. - State SI and CGS units and dimensions of surface energy. - The length of a stretched sonometer wire is 1 m. Where should the bridge be placed to divide the wire into two segments, whose fundamental frequencies are in the ratio 1: 2? - For a common base transistor DC current gain is 0.98. Find the value of current amplification factor. - What is refractive index? State value of refractive index of vacuum? - State the relation for total inductance for series and parallel combination of inductors. - Derive condition for constructive and destructive interference in terms of phase difference, assuming relation for path difference. - A horizontal overhead power line carries a current of 90 A in an east to west direction. What is the magnitude and direction of magnetic field due to the current 1.5 m below the line? **3 marks Questions** - A small-blackened solid copper sphere of radius 2.5 cm is placed in an evacuated chamber. The temperature of the chamber is maintained at 100°C. At what rate energy must be supplied to the copper sphere to maintain its temperature at 110 °C? (Take Stefan's constant σ to be 5.67 × 10-8 Js-1 m-2 K-4, π = 3.1416 and treat the sphere as blackbody.) - What is the experimental observation about threshold frequency? How can it be explained on the basis of Einstein's postulate? - A string breaks under a tension of 10 kg-wt. If the string is used to revolve a body of mass 12 g in a horizontal circle of radius 50 cm, what is the frequency of revolution and linear speed with which the body can be revolved? [g = 9.8 m/s²] - An ideal gas of volume 1.0 L is adiabatically compressed to (1/15)th of its initial volume. Its initial pressure and temperature is 1.01 ×105 Pa and 27 °C respectively. Given Cy for ideal gas = 20.8 J/mol K and γ = 1.4. Calculate - final pressure, - work done, and - final temperature. - (A) Define the following term Beat - (B) On what factors does the internal resistance of a cell depend? - Describe the Geiger-Marsden experiment. State observations from the experiment. - State an expression for displacement of a particle performing S.H.M. Discuss the formula when particle stands from mean position and extreme position respectively. - A capillary tube 2 mm in diameter is immersed in a beaker of mercury. The mercury level inside the tube is found to be 0.5 cm below the level of the reservoir. Determine the contact angle between the mercury and the glass. [Im = 0.4 Nm. Pm = 13.6 103 kg/m³] - Define the following terms: - Coefficient of absorption - Coefficient of reflection - Coefficient of transmission - The maximum value of permeability of a metal (77% Ni, 16% Fe, 5% Cu, 2% Cr) is 0.126 T mA-1. Find the maximum relative permeability and susceptibility. - Derive the Mayer's relation for molar as well as principal specific heats. - In a Zener regulator, source voltage is 25 V, series resistance is of 200 Ω, load resistance is of 500 Ω and Vz = 5 V. Find the minimum Zener current. - Calculate the energies of photons corresponding to ultraviolet light and red light, given that their wavelengths are 3000 Å and 7000 Å respectively. - (A) Define electrostatic potential energy of a system of point charges. - (B) Mention few advantages and disadvantages of solar cell. - Define and explain surface tension. Write down its SI unit and dimensions. - Do we need a banked road for a two-wheeler? Explain. - The two headlights of an approaching automobile are 1.4 m apart. At what maximum distance **4 Marks Questions** - Derive an expression for inductance per unit length near the middle of a long solenoid. - What is parallel resonant circuit? State conditions for parallel resonance. Obtain an expression for resonant frequency. - (A) Derive expression of displacement of a particle performing linear S.H.M. - (B) A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.25 T experiences a torque of magnitude equal to 4.5 × 10-2 J. What is the magnitude of magnetic moment of the magnet? - (A) CGS unit of viscosity is Poise. Find the relation between Poise and the SI unit of viscosity. - (B) Calculate the energy released in the alpha decay of 238Pu to 234U, the masses involved being mPu = 238.04955 u, mU = 234,04095 u and mHe = 4.002603 u. - (A) Obtain an expression for average power dissipated in a purely capacitive circuit. - (B) A hollow cylinder rolls on a horizontal surface with a translational speed of 2 m/s. If its mass is 4 kg and radius of gyration is equal to its radius, then what is the total energy of the rolling motion? - (A) If surfaces of all bodies are continuously emitting radiant energy, why do they not cool down to 0 K? - (B) An X-ray tube produces a continuous spectrum of radiation with its short wavelength end at 0.45 Å. What is the maximum energy of a photon in the radiation?