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

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.

State the Wien's displacement law

Explain the spectral distribution of blackbody radiation.

Choose the correct option:

Two inductor coils with inductance 10 mH and 20 mH are connected in series. What is the resultant inductance of the combination of the two coils?

What is the energy required to build up current of 1A in an inductor of 20 mH?

Obtain the expression for the period of a simple pendulum performing S.H.M.

A simple pendulum performs S.H.M. of period 4 seconds. How much time after crossing the mean position, will the displacement of the bob be one-third of its amplitude.

A simple pendulum of length 100 cm performs S.H.M. Find the restoring force acting on its bob of mass 50 g when the displacement from the mean position is 3 cm.

The string of a guitar is 80 cm long and has a fundamental frequency of 112 Hz. If a guitarist wishes to produce a frequency of 160 Hz, where should the person press the string?

Currents of equal magnitude pass through two long parallel wires having a separation of 1.35 cm. If the force per unit length on each of the wires is 4.76 x 10^-2 N, what must be I ?

Two wires shown in the figure are connected in a series circuit and the same current of 10 A passes through both, but in opposite directions. The separation between the two wires is 8 mm. The length AB is 22 cm. Obtain the direction and magnitude of the magnetic field due to current in wire 2 on the following figure segment AB of wire 1. Also, obtain the magnitude and direction of the force on wire 1. [μ₀ = 4π × 10^-7 T.m/A]

Two long parallel wires, both carrying current I directed into the plane of the page, are separated by a distance R. Show that at a point P equidistant from the wires and subtending an angle θ from the plane containing the wires, the magnitude of the magnetic field is B = `(mu_0)/pi "I"/"R"` sin 2θ. What is the direction of the magnetic field?

A very long straight wire carries a current of 5.2 A. What is the magnitude of the magnetic field at a distance 3.1 cm from the wire?

The magnetic field at a distance of 2.4 cm from a long straight [current-carrying] wire is 16 µT. What is the current through the wire?

The figure shows a cylindrical wire of diameter a, carrying a current I. The current density in the wire is in the direction of the axis and varies linearly with radial distance r from the axis according to the relation J = `"J"_0 "r"/"a"`. Obtain a magnetic field B inside the wire at a distance r from its center.

In the problem, what will be the magnetic field B inside the wire at a distance r from its center, if the current density J is uniform across the cross-section of the wire? Figure shows a section of a very long cylindrical wire of diameter a, carrying a current I. The current density which is in the direction of the central axis of the wire varies linearly with radial distance r from the axis according to the relation J = J_o r/a.

A long solenoid has turns per unit length 1.5 x 10³ per meter and area of cross-section 25 cm². A coil C of 150 turns is wound tightly around the center of the solenoid. For a current of 3 A in the solenoid, calculate
(a) the magnetic flux density at the centre of the solenoid
(b) the flux linkage in the coil C
(c) the average emf induced in coil C if the current in the solenoid is reversed in the direction in a time of 0.5 s. [µ₀ = 4π x 10^-7 H/m]

Insect moves over the surface of water because of ______.

The water droplets are spherical in free fall due to ______