Physics 2017-2018 HSC Science (General) 12th Standard Board Exam Question Paper Solution

In the stationary wave, the distance between a node and its adjacent antinode is _______.

(a) λ

(b) `lambda/4`

(c) `lambda/2`

(d)  2λ

If the source is moving away from the observer, then the apparent frequency _____.

(a) will increase

(b) will remain the same

(c) will be zero

(d) will decrease

A particle of mass m performs the vertical motion in a circle of radius r. Its potential energy at the highest point is _______. (g is acceleration due to gravity)

2 mgr

mgr

0

3 mgr

The compressibility of a substance is the reciprocal of _________.

(a) Young’s modulus

(b) bulk modulus

(c) modulus of rigidity

(d) Poisson's ratio

If the particle starts its motion from mean position, the phase difference between displacement and acceleration is ______.

2π rad 

`pi/2 rad` 

`pi  rad` 

`pi/4 rad`

The kinetic energy per molecule of a gs at temperature T is ________.

(a) `(3/2)RT`

(b) `(3/2)K_BT`

(c) `(2/3) RT`

(d) `(3/2)("RT"/M)`

A thin ring has mass 0.25 kg and radius 0.5 m. Its moment of inertia about an axis passing through its centre and perpendicular to its plane is _______.

0. 0625 kg m²

0.625 kg m²

6. 25 kg m²

62. 5 kg m²

State Kepler's law of orbit and law of equal areas.

State any four assumptions of kinetic theory of gases.

Define moment of inertia. State its SI unit and dimensions.

Distinguish between centripetal and centrifugal force.

In Melde’s experiment, when the tension in the string is 10 g wt then three loops are obtained. Determine the tension in the string required to obtain four loops, if all other conditions are constant.

Calculate the work done in increasing the radius of a soap bubble in air from 1 cm to 2 cm. The surface tension of soap solution is 30 dyne/cm. (Π = 3.142).

A falt curve on a highways has a radius of curvature 400 m. A car goes around a curve at a speed of 32 m/s. What is the minimum value of the coefficient of friction that will prevent the car from sliding? (g = 9.8 m/s²)

A particle performing linear S.H.M. has the maximum velocity of 25 cm/s and maximum acceleration of 100 cm/ m². Find the amplitude and period of oscillation. (π = 3.142)

Derive Laplace’s law for spherical membrane of bubble due to surface tension.

State and prove: Law of conservation of angular momentum.

Calculate the strain energy per unit volume is a brass wire of length 3 m and area of cross - section 0.6 mm² when it is stretched by 3 mm and a force of 6 kgwt is applied to its free end.

What is the decrease in weight of a body of mass 500 kg when it is taken into a mine of depth 1000 km? (Radius of earth R = 6400 km, g = 9.8 m/s²)

State the differential equation of linear simple harmonic motion.

Hence obtain the expression for acceleration, velocity and displacement of a particle performing linear S.H.M.

A body cools from 80° C to 70° C in 5 minutes and to 62° C in the next 5 minutes. Calculate the temperature of the surroundings.

What is meant by harmonics?

Show that only odd harmonics are present as overtones in the case of an air column vibrating in a pipe closed at one end.

The wavelengths of two sound waves in air are `81/173`m and `81/170`m. They produce 10 beats per second. Calculate the velocity of sound in air

The reflected waves from an ionosphere are _____.

(a) ground waves

(b) sky waves

(c) space waves

(d) very high-frequency waves

In interference pattern, using two coherent sources of light; the fringe width is ________

(a) directly proportional to the wavelength

(b) inversely proportional to the square of the wavelength

(c) inversely proportional to wavelength.

(d) directly proportional to the square of the wavelength.

Electric intensity outside a charged cylinder having the charge per unit length 'λ' at a distance from its axis is ________.

(a) E = `(2pi in_0 lambda)/(Kr^2)`

(b) E = `(in_0 lambda)/(2piKr^2)`

(c) E = `lambda/(2piin_0Kr)`

(d) E = `(4piin_0lambda)/(Kr^2)`

SI unit of potential gradient is _______.

(a) V cm

(b) `V/"cm"`

(c) Vm

(d) `V/m`

The momentum associated with the photon is given by_______.

(a) hv

(b) `"hv"/c`

(c) hE

(d) hλ

A pure semiconductor is ________.

(a) an extrinsic semiconductor

(b) an intrinsic semiconductor

(c) p-type semiconductor

(d) n-type semiconductor

The glass plate of refractive index 1.732 is to be used as a polarizer, its polarising angle is _______.

30°

45°

60°

90°

State the conditions to get constructive and destructive interference of light.

State Ampere’s circuital law.

Explain Ampere’s circuital law.

Draw the block diagram of a receiver in communication system

State formula and S.I. unit of Magnetization.

The electron in the hydrogen atom is moving with a speed of 2.3x10⁶ m/s in an orbit of radius 0.53 Å. Calculate the period of revolution of the electron. (Π = 3.142)

A capacitor of capacitance 0.5 μF is connected to a source of alternating e.m.f. of frequency 100 Hz. What is the capacitive reactance? (Π = 3.142)

Calculate the de-Broglie wavelength of an electron moving with one-fifth of the speed of light.Neglect relativistic effects. (`h = 6.63 xx 10^(-34)` J.s, c= `3xx10^8`m/s, mass of electron = `9 xx 10^(-31) kg)`

For proton acceleration, a cyclotron is used in which a magnetic field of 1.4 Wb/m² is applied. Find the time period for reversing the electric field between the two Ds.

Explain with a neat circuit diagram how will you determine unknown resistance ‘X' by using meter bridge

What is Zener diode?

Describe, with the help of a circuit diagram, the working of Zener diode as a voltage regulator.

In a biprism experiment, the light of wavelength 5200Å is used to get an interference pattern on the screen. The fringe width changes by 1.3 mm when the screen is moved towards biprism by 50 cm. Find the distance between two virtual images of the slit.

The refractive indices of water and diamond are `4/3` and 2.42 respectively. Find the speed of light in water and diamond. (c = 3x10⁸ m/s)

Prove theoretically the relation between e.m.f. induced in a coil and rate of change of magnetic flux in electromagnetic induction.

A parallel plate air condenser has a capacity of 20µF. What will be a new capacity if:

1) the distance between the two plates is doubled?

2) a marble slab of dielectric constant 8 is introduced between the two plates?

The work function for a metal surface is 2.2eV. If the light of wavelength 5000Å is incident on the surface of the metal, find the threshold frequency and incident frequency. Will there be an emission of photoelectrons or not? (c = 3 x 10⁸ m/ s, 1eV = 1.6x10^-19 J , h = 6.63 x 10^-34 J.s.)