Pre – Board Examination (2074
-12 -23)
Sun –Rise English School
Students should give their answers in their own words as
far as practicable
Class: XI
subject: physics
Time: 3 Hours
Full marks: 75
Pass grade: C
Group A
(1) Answer, in brief, any SIX questions:
(2 x6 =12)
a) What is the difference between accurate and precise
measurement?
b) Can you have a zero acceleration but non – zero velocity? Explain
with help of a graph.
c) Sand is thrown on the roads covered with snow. Why?
d) What is black hole? Write down its characteristic features.
e) A bucket containing water is rotated in a vertical circle. Why does
not water fall?
f) Explain which one is more elastic – rubber or steel.
g) In usual notation, a simple harmonic motion is given as y = asin
( wt −∅ ) . Find its acceleration.
(2) Answer, in brief, any TWO questions:
(2 x 2 =4)
a) Two bodies made of the same material have the same external
dimension and appearance, but one is hollow and other is solid. When
they are heated, is the overall volume expansion the same or different?
b) At a fixed temperature, the volume of a vessel is compressed to half.
How will the rms speed of the gas in it change?
c) Explain why temperature of gas drops in adiabatic expansion.
(3) Answer, in brief, any ONE question:
(2 x 1 =2)
a) Why does a clear pool of water always appear to be shallower than
it actually is?
b) How is dispersive power related to refractive index of the material?
(4) Answer, in brief, any ONE question:
(2 x 1 =2)
a) Why a man inside an insulated hollow metal cage does not receive a
shock although it is connected to a high voltage supply?
b) Define dielectric constant and dielectric strength.
Group B
(5) Answer any THREE questions:
(4 x 3 =12)
a) State triangle law of vector addition. Obtain an expression for the
resultant of two vectors P and Q inclined at angleθ.
b) Define work. Derive an expression to calculate work done by a
variable force.
c) What is a simple pendulum? Show that motion of the bob of simple
pendulum is simple harmonic, Obtain an expression for its time period.
d) What is capillarity? Find the expression for the height of liquid
column in a capillary tube when dipped partially in a liquid.
(6) Answer any TWO questions:
(4 X 2 =8)
a) Define latent heat of fusion of ice. Explain the method of
determining the latent heat of fusion of ice by the method of mixture.
b) Describe Searle’s method of determination of thermal conductivity
of a good conductor.
c) Explain the working of a diesel engine with the help of P – V diagram.
(7) Answer any ONE question:
(4 x 1 =4)
a) What is lateral shift? Derive an expression for its value. How does
the lateral shift change with the increase in the angle of incidence?
b) Describe the construction and working of a refraction type
astronomical telescope. Obtain its angular magnification when the final
image is formed at infinity.
(8) Answer any ONE question:
(4 x 1 =4)
a) State Gauss law. Use this theorem to find the electric field intensity
due to a plane charged conductor.
b) What is a capacitor? Find an expression for the energy stored in a
charged capacitor.
Group C
(9) Solve any THREE numerical questions:
(4 x 3 =12)
a) A projectile is launched with an initial velocity of 30ms -1 at an angle
of 600 above the horizontal. Calculate the magnitude and direction of
its velocity 5 second after launch.
b) What would be the acceleration of a block sliding down an inclined
plane that makes an angle of 450 with the horizontal if the coefficient of
sliding friction between two surfaces is 0.3?
c) Assuming the earth to be uniform sphere of radius 6400 Km,
calculate the total energy needed to raise a satellite of mass 2000 Kg to
a height of 800 Km , above the surface of the earth and to set it into
circular orbit at that altitude.
d) A uniform steel wire of density 7800 Kgm-3 weights 16 gram and is
250 cm. It lengthens by 1.2 mm when a load of 8kg is applied. Calculate
the value of Young’s modulus for the steel and the energy stored in the
wire. (g=10 ms-2)
(10) Solve any TWO numerical questions:
(4 x 2 =8)
a) What is the result of mixing 100 gm of ice at 0 0c into 100 gm of water
at 20 0c in an iron vessel of mass 100 gm? (Specific heat capacity of iron
= 0.1 cal g-1 0c-1, latent heat of ice = 80 cal / gm)
b) Estimate the rate at which ice would melt in a wooden box 2.5 cm.
thick of inside measurement 100 cm x 60 cm x 40 cm. assuming that the
external temperature is 350c and thermal conductivity of wood is 0.168
W m-1 k-1. [Latent heat of fusion of ice = 336 x 10 3 J kg-1]
c) The density of a gas is 1.775 Kgm-3 at 27 0c and 105 Nm-2 pressures
and its specific heat capacity at constant pressure is 846 JKg-1k-1. Find
the ratio of its specific heat capacity at constant pressure to that at
constant volume.
(11) The refractive index of an equilateral prism is 1.53. What is the
limiting angle of incidence of a ray that will be transmitted through the
prism? (4)
(12) What distance must an electron move in a uniform potential
gradient of 200 V/cm in order to gain kinetic energy 3.2 x 10-18 J?
(3)
Good luck!!
