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

The periodic time of a linear harmonic oscillator is 2π second, with maximum displacement of 1 cm. If the particle starts from extreme position, find the displacement of the particle after π/3  seconds.

Show that all harmonics are present on a stretched string between two rigid supports.

State Bohr’s third postulate for hydrogen (H2) atom. Derive Bohr’s formula for the wave number. Obtain expressions for longest and shortest wavelength of spectral lines in ultraviolet region for hydrogen atom

The photoelectric current in a photoelectric cell can be reduced to zero by a stopping potential of 1.8 volt. Monochromatic light of wavelength 2200Å is incident on the cathode. Find the maximum kinetic energy of the photoelectrons in joules. [Charge on electron = 1.6 x 10^-19 C]

Draw a neat labelled circuit diagram of experimental arrangement for study of photoelectric effect.

A parallel beam of monochromatic light is incident on a glass slab at an angle of incidence 60^o. Find the ratio of width of the beam in the glass to that in the air if refractive index of glass is 3/2.

The co-efficient of reflection of an opaque body is 0.16. Its co-efficient of emission is ........................................

1. 0.94
2. 0.84
3. 0.74
4. 0.64

Draw neat, labelled diagrams for the modes of vibration of a stretched string in second harmonic and third harmonic.

Explain the formation of energy band diagram in case of conductor and semiconductor.

State the conditions to get steady interference pattern.

In a hydrogen atom, an electron carrying charge 'e' revolves in an orbit of radius 'r' with speed 'v'. Obtain an expression for the magnitude of magnetic moment of a revolving electron.

A solenoid of length 1.5 m and 4 cm in diameter possesses 10 turns per metre. A current of 5 A is flowing through it. The magnetic induction at a point inside the solenoid along the axis is ............................. .

(μ₀ = 4π × 10^-7 Wb/Am)

1. π  × 10^-5 T
2. 2π × 10^-5 T
3. 3π × 10^-5 T
4. 4π × 10^-5 T

A solenoid of length 1.5 m and 4 cm in diameter possesses 10 turns per metre. A current of 5 A is flowing through it. The magnetic induction at a point inside the solenoid along the axis is ............................. .

(μ₀ = 4π × 10^-7 Wb/Am)

1. π  × 10^-5 T
2. 2π × 10^-5 T
3. 3π × 10^-5 T
4. 4π × 10^-5 T

The photoelectric work function for a metal is 4.2 eV. If  the stopping potential is 3V, find the threshold wavelength and maximum kinetic energy of emitted electrons. 

(Velocity of light in air = 3 x 10⁸m/s,
Planck's constant = 6·63 x10^-34 J -s,
Charg.e ori electron = 1·6 x 10 ^-19 C)

A copper metal cube has each side of length 1 m. The bottom edge of the cube is fixed and tangential force 4.2x10⁸ N is applied to a top surface. Calculate the lateral displacement of the top surface if modulus of rigidity of copper is 14x10¹⁰ N/m².

A metal rod `1/sqrtpi `m long rotates about one of its ends perpendicular to a plane whose magnetic induction is 4 x 10^-3 T. Calculate the number of revolutions made by the rod per second if the e.m.f. induced between the ends of the rod is 16 mV.

A metal rod `1/sqrtpi `m long rotates about one of its ends perpendicular to a plane whose magnetic induction is 4 x 10^-3 T. Calculate the number of revolutions made by the rod per second if the e.m.f. induced between the ends of the rod is 16 mV.

State Ampere’s circuital law.

Calculate the radius of second Bohr orbit in hydrogen atom from the given data.

Mass of electron = 9.1 x 10^-31kg

Charge on the electron = 1.6 x 10^-19 C

Planck’s constant = 6.63 x 10^-34 J-s.

Permittivity of free space = 8.85 x 10^-12 C²/Nm²

State Ampere’s circuital law.