SAHIWAL BOARD 2013
PAPER PHYSICS
PART-I
Time: 20 Min.
(Objective Part)
Marks: 17
Note: You have four choice for each objective type question as A,B,C and D. The choice which you think is correct; fill that circle in front of that question number. Use marker or pen to fill the circles. Cutting or filling two or more circles will result in zero mark in that question.

• The frequency of waves produce in microwave oven is :

(a) 1450 MHz
(b) 1650 MHz
(c) 2450 MHz
(d) 2850 MHz

• Tuning a radio is example of :

(a) Mechanical resonance
(b) Light vaton nce
(c) Electrical resonance
(d) Physical resonance

• The distance between Node and Antinodes:

(a) 4λ
(b) 2 λ
(c) λ /2
(d) λ /4

• Wavelength of X-rays is of the order of :

(a) 10^-10m
(b) 10^-8m
(c) 10^-1m
(d) 10^-4m

• The minimum distance from the eye at which an object appears to be distinct.

(a) 15 cm
(b) 20 cm
(c) 25 cm
(d) 30 cm

• The unit of entropy is :

(a) JK
(b) K/J
(c) J
(d) J/K

• The concept of entropy was introduced by Rudolph Clauses is:

(a) 1840
(b) 1856
(c) 1857
(d) 1905

• Significant figure in 0.00846 are :

(a) Three
(b) Four
(c) Six
(d) Seven

• If R_x and R_y both are negative, then the direction of resultant vector lies in :

(a) 1st quadrant
(b)2^nd quadrant
(c) 3^rd quadrant
(d) 4^th quadrant

• Motion of projectile is :

(a) One dimension
(b) Two dimension
(c) Three dimension
(d) Four dimension

• For maximum range , the angle of projection must be :

(a) 30'
(b) 45°
(c) 60°
(d) 90°

• Work is a negative when angle between F and d is :

(a) 0°
(b) 900
(c) 45°
(d) 180°.

• The SI unit of angular momentum is :

(a) JS
(b) NS
(c) Joule
(d) Newton

• A Geo-stationary satellite occupies a longitude of :

(a) 90°
(b) 100°
(c) 120°
(d) 150°

• The direction of angular velocity is found by :

(a) Left and rule
(b) Head to tail rule
(c) Right hand rule
(d) General rule

• The density of blood is nearly equal to:

(a) Air
(b) Water
(c) Milk
(d) Honey

• Distance covered during one vibration of an oscillating body in terms of amplitude A.

(a) A/2
(b) A
(c) 2A
(d) 4A

Time: 3:10 hours
(Subjective Part)
Marks: 83

Section II

2. Attempt any EIGHT short questions. (8 x 2 =16)

• The period of simple pendulum is measured by a stop watch. What type of errors are possible '?
  
• How many nanoseconds are there in one year?
  
• What are dimensions and units of gravitational constant G in the: Formula F=Gm₁m₂ R²
  
• Differentiate between precise measurement and accurate measurement.
  
• Can you add zero to a null vector ?
  
• Can a body rotate about its centre of gravity under the action of its weight?
  
• Define the terms. (i) Null vector (ii) Equal vector
  
• Find the change in momentum for an object subjected to a given force for a given time.
  
• At what point or points in it's path does a projectile have minimum speed , it's maximum speed .
  
• How does a rocket move. Explain '?
  
• What is impulse give its dimensions ?
  
• Two row boats moving parallel in the same direction are pulled towards each other. Explain .

3. Attempt any EIGHT short questions. (8 x 2 = 16)

• Define conservative force, give its one example.
  
• Calculate the work done in kilojoule in lifting a mass of 10kg through a vertical height of 10m.
  
• An object has 1.j of potential energy . Explain what does it mean.
  
• What is meant by real and apparent weight '?
  
• What is meant by moment of inertia ? Explain its significance.
  
• Show that orbital angular momentum L_o= mvr
  
• Define resonance . Write its one example.
  
• Name two characteristics of simple harmonic motion .
  
• Describe some common phenomenon in which resonance plays an important role?
  
• Distinguish between transverse waves and longitudinal waves .
  
• Explain the terms through , crest, node and antinode.
  
• Explain why should travels faster in warmer air than in cold air?

4. Attempt any SIX short questions. (6 x 2 = 12)

• How would you distinguish between unpolarized and plane polarized lights'?
• Could you obtain Newton's Rings with transitted light? If yes , would the pattern be different from that obtained with reflected light.
• What are the difference between interference frings and diffraction fringes?
• Explain the differene between angular manification and resolving power .
• If a person was looking through a telescope at full moon, how would the appearance of the moon be changed by covering half of the objective lens?
• Why is the average velocity of the molecules in a gas zero but the average of the square of velocities is not zero ?
• What happens to the temperature of the room when an air conditioner is left running on a table in the middle of the room?
• Derive Boyl's law from kinetic molecular theory of gasses.
• What is average translational kinetic energy of the molecules in a gas at 28°C?

SECTION-III

Attempt any THREE questions. (8 x 3 = 24)

5. (a) What is rectangular components? Describe the method of vector addition by rectangular components.(1,4)
(b) A football is throw upward at an angle of 30° C with respect to horizontal . To throw a 40 m Pass , what must be the initial speed of the ball'?(3)

6. (a) Define centripetal force and derive its relation .(5)
(b) 100cm³ of water is pumped from a reservoir into a tank 10 m higher than the reservoir in 20 min. If density of water is 1000kg.m^-3, find the power delivered by the pump. (3)

7. (a) What is simple pendulum '? Show that simple pendulum execute simple harmonic motion. Find out its time period.(1,3,1)
(b) A church organ consists of pipes , each open at one end of different lengths. The minimum length is 30 mm and the longest is 4 m.Calculate the frequency range of the fundamental notes. (Speed of sound = 340m/s).

8. (a) Explain Michelson interferometer i.e construction and working.(1,4)
(b) A telescope is made of an objective of focal length 20 cm and an eye piece of focal length 5 cm , both convexlens find angular magnification.(3)

9.(a) State and prove Bernoulli's equation.(5)
(b) A mechanical engineer develops an engine, working between 327°C and 27°C and claim to have an efficiency of 52%. Does he claim correctly ? Explain .(3)

SECTION-IV

10. Attempt any THREE questions. (5x 3 = 15)

• (a)Define vernier constant of vernier calliper . Find the vernier constant if the smallest division on main scale is 1 mm and total division on vernier scale is 20.(4x2=8)
• Design a table of observations / calculations to find the weight of a body by method of vector addition.
• What are the sources of error in the experiment to determiAe the moment of inertia of fly wheel'?
• Why does the paper rider fly off a fixed length of wire of sonometer?
• What is the end correction in resonance tube experiment and how it is determine'?
• Does the critical angle of a transparent material varies with the colour of light?
• Design a table of observation / calculations to determine the focal length of convex lens by displacement method.
• What precautions should be observed in the experiment time period is independent of the amplitude of simple pendulum?

(b) write down the brief procedure to varify that time period of simple pendulum is independent of mass of bob (3)

OR

Write down brief procedure to determine experimentally the focal length of convex lens by displacement method.

(c) Answer the following questions on the basis of graph " A " below.(4)

• What do you conclude from the graph?

Image

• Find the focal length of the lens from the graph.

OR

• Answer the following question on the basis of graph "B" below

Image

• What is the the relation between L and T²?
• Find the value of "g" from the graph.