HSC Science (General) 12th Standard Board Exam - Maharashtra State Board Question Bank Solutions

Are Kirchhoff’s laws applicable to both AC and DC currents?

Answer in Brief:

Part of a racing track is to be designed for curvature of 72m. We are not recommending the vehicles to drive faster than 216 kmph. With what angle should the road be tilted? By what height will its outer edge be, with respect to the inner edge if the track is 10 m wide?

A road is constructed part of a racing tracks to be designed with radius of curvature 72 m. We are not recommending the vehieles to drive faster than 216 kmph.. The coefficient of static friction between the tyres of a vehicle on this road is 0.8, will there be any lower speed limit? By how much can the upper speed limit exceed in this case?

(Given: r = 72 m, vo = 216 km/h, w = 10 m, θ = 78°4', h = 9.805 m)

During a stunt, a cyclist (considered to be a particle) is undertaking horizontal circles inside a cylindrical well of radius 6.05 m. If the necessary friction coefficient is 0.5, how much minimum speed should the stunt artist maintain? The mass of the artist is 50 kg. If she/he increases the speed by 20%, how much will the force of friction be?

A pendulum consisting of a massless string of length 20 cm and a tiny bob of mass 100 g is set up as a conical pendulum. Its bob now performs 75 rpm. Calculate kinetic energy and increase in the gravitational potential energy of the bob. (Use π² = 10)

Two cells of emf 1.5 Volt and 2 Volt having respective internal resistances of 1 Ω and 2 Ω are connected in parallel so as to send current in the same direction through an external resistance of 5 Ω. Find the current through the external resistance.

A metallic ring of mass 1 kg has a moment of inertia 1 kg m² when rotating about one of its diameters. It is molten and remolded into a thin uniform disc of the same radius. How much will its moment of inertia be, when rotated about its own axis.

The energy stored in a soap bubble of diameter 6 cm and T = 0.04 N/m is nearly ______.

Why is the surface tension of paints and lubricating oils kept low?

How much amount of work is done in forming a soap bubble of radius r?

Explain the capillary action.

Derive an expression for capillary rise for a liquid having a concave meniscus.

Calculate the rise of water inside a clean glass capillary tube of radius 0.1 mm, when immersed in water of surface tension 7 × 10^-2 N/m. The angle of contact between water and glass is zero, the density of water = 1000 kg/m³, g = 9.8 m/s².

Twenty-seven droplets of water, each of radius 0.1 mm coalesce into a single drop. Find the change in surface energy. Surface tension of water is 0.072 N/m.

A drop of mercury of radius 0.2 cm is broken into 8 droplets of the same size. Find the work done if the surface tension of mercury is 435.5 dyn/cm.

Choose the correct option.

The mean free path λ of molecules is given by where n is the number of molecules per unit volume and d is the diameter of the molecules. 

Obtain an expression for the orbital magnetic moment of an electron rotating about the nucleus in an atom.

Choose the correct option:

The length of second's pendulum on the surface of earth is nearly 1 m. Its length on the surface of moon should be [Given: acceleration due to gravity (g) on moon is `1/6` th of that on the earth’s surface]