12th Science Maharashtra Board
In this category students supposed to ask questions which belong to std 12th maharashtra board Science
- When seen from below, the blades of a ceiling fan are seen to be revolving anticlockwise and their speed is decreasing. Correct answer is (B) Angular velocity downwards, angular acceleration upwards. 1
- A big dumb-bell is prepared by using a uniform rod of mass 60 g and length 20 cm. Two identical solid spheres of mass 50 g Answer: I = 46000\ mathrmg cm² = 4.6×10⁻³\ mathrmkg m² Given: rod M_r = 60\ g , L = 20\ cm ; each sphere M_s = 50\ g , R_s = 10\ cm . Distan... 1
- A flywheel used to prepare earthenware pots is set into rotation at 100 rpm. It is in the form of a disc Given : f_(1 )= 100 rpm, f₂= 80 rpm, M =10 kg, R = 0.4m, m = 1.6kg I₁=I_(wheel )= 1/2 MR² = 1/2(10)(0.4)² ^( )= 0.8 kg m² MI of the wheel an... 1
- The road in the question 14 above is constructed as per the requirements. Given : r=72m, θ= 78°4’ , μ_s=0.8, g= 10m/s^(2 ), tanθ= tan78^(°)4’ =5 V_min =√(rg(tanθ-μ_s/1+μ_stanθ)) V_min= √(72×10(5-0.8/1+(0.8((5))) v_... 1
- A metallic ring of mass 1 kg has moment of inertia 1 kg m2 when rotating about one of its diameters The MI of the thin ring about its diameter, Ir = 1/2MR² = 1 kg\ m² Since the ring is melted and recast into a thin disc of same radius R, th... 1
- State and explain the principle of conservation of angular momentum. Use a suitable illustration. Do we use it in our daily life? When? Law (or principle) of conservation of angular momentum : The angular momentum of a body is conserved if the resultant external torque on the... 1
- Derive an expression that relates angular momentum with the angular velocity of a rigid body. Consider a rigid body rotating with a constant angular velocity w about an axis through the point O and perpendicular to the plane of the fi... 1
- State the conditions under which the theorems of parallel axes and perpendicular axes are applicable. The theorem of parallel axis is applicable to any body of arbitrary shape. The moment of inertia (MI) of the body about an axis through the... 1
- Using the energy conservation, derive the expressions for the minimum speeds at different locations along a Consider a particle of mass m attached to a string and revolved in vertical circle of radius r, At every instant of motion there are only tw... 2
- While driving along an unbanked circular road, a two-wheeler rider has to lean with the vertical. (i) When a bicyclist takes a turn along an unbanked road, the force of friction Fs provides the centripetal force; the normal reaction of th... 1
- Why is it useful to define radius of gyration? Radius of gyration is defined as the distance from the axis of rotation to a point where the total mass of the body is supposed to be concen... 2
- What are diamagnetic substances? The diamagnetic materials are those materials which weakly repel the external magnetic field. 1
- Name the bravais lattice in the triclinic system The bravais lattice in the triclinic system is a simple or primitive unit cell. 1
- Write the effect on density of a substance in the Frenkel defect? The density remains unchanged in Frenkel defect. In the frenkel defect an ion takes a place at an interstitial position. Hence there is no i... 1
- Explain with diagram the boiling point elevation in terms of vapour pressure lowering ? The boiling point of a liquid is the temperature at which the vapour pressure of the liquid becomes equal to the atmospheric pressure. For E... 2
- What is osmotic pressure ? Chemistry 12th osmosis is a flow of solvent through a semipermeable membrane into the solution. The direction of osmosis can be reversed by applying a pres... 2
- A gas contained in a cylinder fitted with a frictionless piston expands against a constant external pressure of 1 atm 106.5 J is the correct answer Solution:: 2
- If A and B are two skew-symmetric matrices of order n, then, (a) AB is a skew-symmetric matrix (c) is the correct option We are given A’ = -A and B’ = -B; Now, (AB)’ = B’;A’ = (-B) (-A) = BA = AB, if A and B commute. 1
- [MCQ ] Molecular solids are __________ crystalline solids amorphous solids a) crystalline solids , is the correct answer 2
- Niobium forms bcc structure the density of niobium is 8.55 g/cm3 and length of unit cell edge the correct answer is 1.62 × 10²^(1 ) EXplaination ^() 2
- Alluminium crystallizes in cubic close packed structure with unit cell edge 353.6 pm correct answer is r=125pm units=2.26×10²² Explanation https://youtu.be/RoQib35FfB4 1
- The density of iridium is 22.4 g/cm3 . The unit cell of iridium is fcc. Calculate the radius of iridium atom. Molar mass of iridium is 192.2 g/mol. The correct answer is 136 pm Explanation:: 1
- Draw the energy band diagram when intrinsic semiconductor (Ge) is doped with impurity atoms of Antimony (Sb). Answer :diagram: 2
- A gas contained in a cylinder fitted with a frictionless piston expands against a constant external pressure of 1 atm from triangle V =10-5=5 space litre=5×10³ m³ Q=400J space ,space space P=1atm =1.013×10⁻⁵ pa W=p.dV= 1.013×10⁵ ×5 ×10⁻³ =506.5 J triangle U=Q-W =... 1