Sahiwal Board 2015
Physics
Inter (Part-I)
(Objective Type)
Time Allowed: 20 Minutes
Max. Marks: 17
Note: You have four choices 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.

Question #1
Circle the correct option i.e. A/B/C/D. Each part carries one mark.

• Isothermal process is carried out at constant

(a) Volume
(b) Pressure
(c) Entropy
(d) Temperature

• The SI unit of entropy is:

(a) JK^-1
(b)J^-1K
(c)JK
(d) J^-1 K^-1

• The least distance of distinct vision for normal eeye is:

(a) 5 cm
(b) 10 cm
(c) 25 cm
(d) 50 cm

• Which phenomenon of light proves that light waves are transverse in nature?

(a) Refraction
(b) Reflection
(c) Diffraction
(d) Polarization

• If a string vibrates in 'n' loops, then wavelength of stationary waves will be

(a) 2l/n
(b) nl/n
(c) 2/l
(d) l/2

• The velocity of sound in vacuum is:

(a) 332 m/s
(b) 333 m/s
(c) 280 m/s
(d) zero

• The frequency of sound's pendulum is:

(a) 1 Hz
(b) 0.5 Hz
(c) 1.5 Hz
(d) 2 Hz

• One torr is equal to:

(a) 13.33 Nm^-2
(b) 1.333Nm^-2
(c) 133.3Nm^-2
(d) 1333 Nm^-2

• Which one of the following is correct?

(a) ω = vr
(b) v = r/ω
(c) v = rω
(d) ω = r/v

• The angle subtened`ed at the centre by circumference of a circle is:

(a) πrad
(b) 3π rad
(c) 2π rad
(d) π/2 rad

• One radian is equal to:

(a) 67.3°
(b) 57.3°
(c) 87.3°
(d) 45°

• The work done is negative when angle between force and displacement is

(a) 45°
(b) 90°
(c) 0°
(d) 180°

• The rate of change in momentum of a body is equal to:

(a) Displacement
(b) Velocity
(c) Acceleration
(d) Applied force

• 15 The horizontal component of velocity of projectile

(a) Increases
(b) Decreases
(c) Remains same
(d) Decreases and then increases

• The resultant of two forces 3N and 4N acting at right angle to each other is:

(a) 5N
(b) 6N
(c) 1N
(d) 7N

• Which is not a base unit in SI units?

(a) Kilogram
(b) Joule
(c) Ampere
(d) Kelvin

Sahiwal Board 2015
Physics
Inter (Part-I)
(Subjective)
Time Allowed: 3.10 Hours 
Max. Marks: 83 
Section-I

2. Write short answers to any eight parts. (8x2 =16)

1.  Name several repetitive phenomenon occurring in nature which could service as reasonable time standards.
2.  Find the dimensions and hence the SI units of co-efficient of viscosity.
3.  Define (i) Radian (ii) Steradian
4.  How many meters are there in one light year?
5.  When a body is in (i) Translational equilibrium (ii) Rotational equilibrium
6.  Name the three different conditions that could make ?
7. Two vectors have unequal magnitudes. Can their sum be zero? Explain.
8. Show that the area between the velocity time graph and time axis is numerically equal to the distance covered by the object.
9. Prove that time rate of change of momentum of a body equals the applied force.
10. At what point in the path does a projectile have its minimum speed its maximum speed.
11. Explain the circumstances in which the velocity and acceleration of a car are (i) parallel (ii) Perpendicular to one another
12. Explain how the swing is produced in a fast moving cricket ball.

3. Write short answers to any eight parts. (8x 2 =16)

1. Calculate the work done in kilo joules in lifting a mass of 10 kg through a vertical height of 10 m.
2. A force F acts through a distance L The force is then increased to 3F, and then acts through a further distance of 21.. Draw the work diagram to scale.
3. Differentiate between tangential velocity and angular velocity.
4. When a body is in (i) Translational equilibrium (ii) rotational equilibrium
5. What is tidal energy?
6. Does frequency depend on amplitude for harmonic oscillators?
7. Can wwe realize an ideal simple pendulum?
8. What is meant by phase angle? Does it define angle between maximum displacement and the driving force?
9. What is effect of pressure and density on speed of sound?
10. How should a sound source move with respect to an observer so that the frequency of its sound does not change?
11. Is it possible for two identical waves travelling in the same line direction along a string to give rise to a stationary wave?

4. Write short answers to any six parts. ( 6x 2 =12 )

1. Under what conditions two or more sources of light behave as coherent sources?
2. Why the polarized sunglasses are better than ordinary sunglasses?
3. How would you distinguish between unpolarized and plane polarized lights?
4. Define magnifying power and resolving power of an optical instrument.
5. Why would it be advantageous to use blue light with compound microscope?
6. How the light signal is transmitted through the optical fiber?
7. Specific heat of a gas at constant pressure is greater than specific heat at constant volume. Why?
8. Is it possible to convert internal energy into mechanical energy. Explain with an example.
9. Define reversible and irreversible process

SECTION-II

Note: Attempt any three (3) questions. (3x8=24)

 Question #5
(a) Define rectangular components of a vector. Find resultant of two vectors by their rectangular components.
(b) A proton moving with a speed of 1.0 10⁷ ms^-1 passes through a 0.02 cm thick sheet of paper and emerges with a speed of 2.0 10⁵ms^{-1 .}Assuming the uniform deceleration, find retardation and time taken to pass through the paper.

 Question #6
(a) Define absolute potential energy. Derive its mathematical expression.
(b) The earth rotates on its axis once a day. Suppose by some process the earth contracts so that its radius is only half as large as at present. How fast it will be rotating then?

 Question #7
(a) Show that the total energy of the vibrating mass and spring is constant.
(b) Find the temperature at which the velocity of sound in air is two times its velocity at 10°C.

 Question #8
(a) Explain the diffraction of x-rays by crystals. What are uses of diffraction of x-rays?
(b) As astronomical telescope having magnifying power of 5 consist of two thin lenses 24 cm apart. Find the focal lengths of the lenses.

 Question #9
(a) State and prove Bernoulli’s equation.
(b) A heat engine performs 1001 of work and at same time rejects 4001 of heat energy to the cold reservoir. What is the efficiency of the engine?