HSC Science (Computer Science) १२ वीं कक्षा - Maharashtra State Board Question Bank Solutions for Physics

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 ______ 

The surface tension of a liquid at critical temperature is ______ 

Define surface tension.

What will be the shape of the liquid meniscus for the obtuse angle of contact? 

Water rises to a height of 20 mm in a capillary tube. If the radius made 1/3^rd of its previous value, to what height will the water now rise in the tube?  

Two soap bubbles have a radius in the ratio of 2:3. Compare the works done in blowing these bubbles.  

Explain the phenomena of surface tension on the basis of molecular theory.

Obtain an expression for the capillary rise or fall using the forces method.  

A u-tube is made up of capillaries of bore 1 mm and 2 mm respectively. The tube is held vertically and partially filled with a liquid of surface tension 49 dyne/cm and zero angles of contact. Calculate the density of the liquid, if the difference in the levels of the meniscus is 1.25 cm. take g = 980 cm/s²  

In a second’s pendulum, the mass of Bob is 50 g. If it is replaced by 100 g mass, then its period will be ______.  

What is a second pendulum?   

Obtain an expression for a time period of the simple pendulum.

A man standing unsymmetrical position between two mountains and fires a gun. He hears the first echo after 1.5 s and the second echo after 2.5 s. If the speed of sound in air is 340 m/s, then the distance between the mountains will be ______ 

An organ pipe of length 0.4 m is open at both ends. The speed of sound in the air is 340 m/s. The fundamental frequency is ______ 

What is the interference of sound waves? 

A string 1 m long is fixed at one end. The other end is moved up and down with a frequency of 20 Hz. Due to this, a stationary wave with four complete loops gets produced on the string. Find the speed of the progressive wave which produces the stationary wave.