Sahiwal Board 2017
Physics
(Objective Type)
Inter (Part-2)
Allowed: 15 minutes
Note: Four possible answers A, B, C and D to each question are given. The choice which you think is correct that circle in front that question with Marker or Pen ink. 'Lining or filling two or more circles 'will result in zero mat k in that question. Write the letter A, B. C or D in the column. (Write correct "option) against each question also. If there k a contradiction in the bubble and hand written answer, bubble option will be considered correct.

• The inductance of n coil can be increased by using:

1. Air as core material
2. Iron as core material
3. Copper as core material
4. Bismuth as core material

• The function of three anodes in a C.R.O is:

1. To accelerate electrons only
2. To focus the electron only
3. To control the brightness of spot on screen
4. To accelerate and focus the electrons

• One Tesla is equal to:

1. NA^-1m^-1
2. NA A^-1
3. Nm^-1A
4. NAm

• When a wire of length ' ' and resistance R is cut into two equal parts then resistivity of each part:

1. Becomes half
2. Remains unchanged
3. Becomes two time
4. Becomes four time.

• One coulomb charge contains the number of electrons

1. 25x10¹⁸
2. 6x10^-19
3. 9x10⁹
4. 6.10¹⁹

• Electro- Encepalo - Graphy (EEG) is the diagnostic test for the working of:

1. Eye
2. Heart
3. Brain
4. Lungs

• The range of weak nuclear force is of the order of:

1. 10^-16 m
2. 10^-14 m
3. 10^-17m
4. 10^-22m

• The decay constant of a radioactive elements depends upon:

1. Nature of material
2. Temperature mute of material
3. Pressure of materials
4. Dimensions of material

• The value of 'Stefan’s constant is:

1. 9x10^-3mk
2. 0974x10⁷m^-1
3. 63x10^-34Js
4. 67x10^-8Wm^-2 k^-4

• The energy of electron in ground slate of hydrogen atom is -13.6eV, then its energy in in the orbit is:

1. -3.4 eV
2. -0.05 eV
3. -54 4 eV
4. -13.6 eV

• If the following particles have the same energy which particle has the shortest wave length:

1. α - particle
2. Neutron
3. β - particle
4. Proton

• The devices which are required to convert various physical quantities into electric voltage are called:

1. Filters
2. Rectifiers
3. Amplifiers
4. Sensors

• The Boolean equation for exclusive OR - gate is given by:

1. X = A.B + B.A
2. X = A.B + A.B
3. A + B + A.B
4. X = A.B + A.B

• The number of crystal systems are:

1. Three
2. Five
3. Seven
4. Fifteen

• If the frequency' of AC supplied is doubled then the capacitive reactance becomes:

1. Half
2. Two times
3. Four times
4. One fourth

• Metal detector consists of:

1. L-C circuit
2. R-L circuit
3. R-C circuit
4. RLC- series circuit

• The condition for a step-down transformer is:

1. N₃>N_p
2. V₃>V_p
3. I_S>I_P
4. Output power greater thaninput power

SUBJECTIVE PART
SECTION B

Q2: Write short answers to any EIGHT (8) questions.

1. What are the differences between electric and gravitational forces?
2. Do electrons tend to region of high potential or of low potential?
3. Electric lines of force never cross. Why?
4. Define the term potential gradient?
5. Who the voltmeter should have a very high resistance?
6. Why does the picture on a 'TV screen become distorted when a magnet is brought near the screen?
7. What should be the orientation of a current carrying coil in a magnetic field so that torque acting upon the coil is maximum? Why?
8. What is dead beat galvanometer?
9. Show that e and have the same units?
10. How would you position a flat loop of wire in a changing magnetic field so that there is no emf induced in the loop?
11. Can a D.C motor be turned into a D.C generator'? What changes are required to be done?
12. Can a step up transformer increase the power level'? Explain.

Q3. Write short answers to any EIGHT (8) questions.

1. What are difficulties in testing whether the filament of a lighted bulb obeys Ohm's Law?
2. What is temperature co-efficient of resistance?
3. What is unit of electric current? Define it.
4. What is meant by hysteresis loss?
5. What are ductile and brittle substances? Give an example of each.
6. Describe difference between proportional limit and elastic limit.
7. How the reception of a particular radio station is selected on your radio set?
8. Differentiate between amplitude modulation and frequency modulation.
9. Explain the principle of metal detector.
10. What is effect of forward biasing of a diode on width of depletion region?
11. Give two applications agates in control system.
12. Draw the symbols of pop and non-transistors.

Q4.Write short answers to any SIX (6) questions.

1. Write down two uses of photocell.
2. If the speed or light were infinite. What would be the equations of special theory of relativities reduce to?
3. When light shines on a surface is momentum transferred to the metal surface?
4. How the spectrums of hydrogen can contain so many lines, when hydrogen contains one electron?
5. Is energy conserved when an atom emits a photon of light?
6. What is fusion reaction?
7. What is meant by absorbed dose also write down the units of absorbed dose?
8. What do you know about background radiation? State two sources of this radiation.
9. What factors make a fusion reaction difficult to achieve?

SECTION C

Note: Attempt any THREE questions.

Q5.

1. State and explain Ohm's Law.
2. Two point charges. q₁= -1.0 x 10_-6 C and q₂= -4.0x10^-6 are separated by a distance of 3.0m. Find and justify the zero field location.

Q6.

1. What is a transformer? Describe its principle, construction and working.
2. How fast must a proton move in a magnetic field of 2.50 x 10^-3T such that magnetic force is equal to its weight?

Q7.

1. Define rectification. What are its types Discuss half wave rectification.
2. An alternating source of emf 12 V and frequency 50Hz is applied to a capacitor of capacitance 3 F in series with a resistor of resistance IK Calculate the phase angle.

Q8.

1. Describe the formation of energy hands in solids. Explain the difference among electrical behaviour of 5 conductors insulators and semiconductors in terms of energy band theory.
2. Assuming you radiate as does a black body at your body -temperature about 37° C, at what wavelength do you emit the most energy?

Q9.

1. Explain the terms Meta stable state, stimulated emission and population inversion which are necessary for LASER production.
2. A sheet of lead 5.0 mm thick reduces the intensity of a beam of y-ray by a factor 0.4. Find half value thickness of lead sheet which will reduce the intensity to half of its initial value.