HSC Science (Computer Science) 12th Standard Board Exam - Maharashtra State Board Question Bank Solutions for Physics

Describe how a potentiometer is used to compare the emf's of two cells by the combination method.

Why is a potentiometer preferred over a voltmeter for measuring emf?

The resistance of a potentiometer wire is 8 Ω and its length is 8 m. A resistance box and a 2 V battery are connected in series with iL What should be the resistance in the box if it is desired to have a potential drop of 1 µV/mm?

When two cells of emf's E₁ and E₂ are connected in series so as to assist each other, their balancing length on a potentiometer wire is found to be 2.7 m. When the cells are connected in series so as to oppose each other, the balancing length is found to be 0.3 m. Compare the emf's of the two cells.

The emf of a cell is balanced by a length of 120 cm of a potentiometer wire. When the cell is shunted by a resistance of 10 Ω, the balancing length is reduced by 20 cm. Find the internal resistance of the cell.

A rod of magnetic material of cross-section 0.25 cm² is placed in a magnetizing field of intensity 4000 A/m^-1. The magnetic flux passing through the rod is 25 × 10^-6 Wb. Find out

(a) relative permeability

(b) magnetic susceptibility and 

(c) magnetisation of the rod.

A rod of magnetic material of cross-section 0.25 cm² is placed in a magnetizing field of intensity 4000 A/m^-1. The magnetic flux passing through the rod is 25 × 10^-6 Wb. Find out

(a) relative permeability

(b) magnetic susceptibility and 

(c) magnetisation of the rod.

A uniform magnetic field B(t), pointing upward fills a circular region of radius, s in a horizontal plane. If B is changing with time, find the induced electric field.

The mutual inductance of two coils is 10 mH. If the current in one of the coil changes from 5 A to 1 A in 0.2 s, calculate the emf induced in the other coil. Also calculate the induced charge flowing through the coil if its resistance is 5 Ω.

Derive the relation between α and β.

Which method of biasing is used for operating a transistor as an amplifier?

A diver in a swimming pool bends his head before diving. It ______.

The moment of inertia of a circular loop of radius R, at a distance of R/2 around a rotating axis parallel to horizontal diameter of the loop is ______

Two bodies have their moments of inertia I and 2I respectively about their axis of rotation. If their kinetic energies of rotation are equal, then what is the ratio of their angular velocity.

The moment of inertia of a uniform circular disc about a tangent in its own plane is 5/4MR² where M is the mass and R is the radius of the disc. Find its moment of inertia about an axis through its centre and perpendicular to its plane. 

The moment of inertia of a body about a given axis is 1.2 kgm². initially, the body is at rest. For what duration on the angular acceleration of 25 radian/sec² must be applied about that axis in order to produce rotational kinetic energy of 1500 joule?  

Two wheels of the moment of inertia 4 kgm² rotate side by side at the rate of 120 rev/min and 240 rev/min respectively in the opposite directions. If now both the wheels are coupled by means of a weightless shaft so that both the wheels rotate with a common angular speed. Calculate the new speed of rotation.  

The velocity of the three molecules is 2 km s^-1, 4 km s^-1, 6 km s^-1. Find (i) mean square velocity (ii) root mean square velocity. 

Which of the following is correct, when the energy is transferred to a system from its environment?

Which of the following system freely allows the exchange of energy and matter with its environment?