Class 12, AKHSS Gahkuch 1st term paper solution

 

 

 

Aga Khan Education Service, Pakistan

First Term Examinations Nonember, 2022

          Class – XII

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Physics Paper – I

 

1.      D

2.      C

3.      C

4.      D

5.      A

6.      B

7.      A

8.      B

9.      D

10.  A

11.  C

12.  D

13.  B

14.  C

15.  B

16.  C

17.  A

18.  B

19.  B

20.  A

Physics Paper – II

Q.1) Suppose that you follow an electric field line due to a positive charge. Do the electric field intensity increase or decrease? Support your answer by giving a reason in each case.                                                                                                                       

Ans) Both the quantities will decrease.

Both depends upon the distance from the charge according to the formula

                                   

Q.2) A current carrying conductor is kept between two opposite poles as shown.

In which direction the conductor will move? Also give a reason for it.

 

Ans) According to Flemings left hand rule The conductor will move outwards or out of the page

Due to interaction of two magnetic field or any relevant reason.

Q.3) state three points, how the sensitivity of galvanometer be increased?

           

Ans) The formula for the sensitivity of a galvanometer is

                                                   

So the sensitivity of galvanometer is incresead by either decreasing the c or increasing B, A or N.

 

Q.4) P and Q are two coils arranged parallel to each other and coaxially. Q is connected in series with a battery, a closed switch S and a rheostat R. For each of the following situations, show on a sketch the direction of induced current in P when.

a.         P is moved closed to the Q

b. Q is moved closed to the P

c. The sliding contact of the rheostat R is moved to the right.

Q.5) For a long distance electric supply, step up transformers are used. What will happen if                                                                                                                           (Total 4 Marks)

a.      Step down transformer is used

Ans) More power will be lost

According to joule’s law P = I² R  or any other relevant response.

b.      The primary input is replaced by a DC source.

Mutual induction will not happen      

Since the the flux will not chage in the primary coil or any relevant response   (1 mark)

Q.6) Consider a pure resistive, a pure capacitive and a pure inductive circuits. How the resistance R, the capacitive reactance Xc and inductive reactance XL will change if the frequency of the source is increased.

Ans)

Resistance (R)	constant
Capacitive reactance (XC )	decrease
Inductive reactance (XL )	increase

Q.7) With regards to energy band theory, complete the flowing table for the presence of electron by mentioning empty, partially filled or filled.

 

Material	Valance Band	Conduction Band
Conductors	Filled	Filled
Insulators	Filled	Empty
Semiconductors	Partially filled	Partially filled

 

Attempt either Q.8 OR Q.9.

Q.8) a) Resistance refers to the opposition offered by the comductor to the flow of charges. Name the three factors on which the resistance of the conductor depend? Also mention whether the resistance of semiconductors increases or decreases as a result of rise in temperature.

Ans (a).

 The resistance depends upon  the length, area of corss-section and

    temperature of the  conductor.              R = ρ L/A

   The resistance of semiconductors decreases as a result of rise in temperature.       (01 mark)

b.      State the kirchoffs first rule and mention the law of physics on which this rule is based. Also find the value of I for the given circuit.

Ans) The inward current is positive and outward current is negative.

0.2A -0.4A+ 0.6A – 0.5A+ 0.7A –I = 0

1.5A – 0.9A –I = 0

0.6 A –I = 0

I = 0.6A

Q.9 (a). A current of 0.75 A flows through an iron wire when a source of 1.5 V is connected across its ends. The length of the wire is 5m and its cross sectional area is 1.25 x 10 ^-7 m^2. Calculate the specific resistance of the iron.                                                            (Total 8 Marks)

Ans) (a).   Correct formula i.e.   (1 mark)

Correct answer with unit i.e 2          (1 mark)

Correct formula i.e.                 (1 mark)

Correct answer with unit i.e. (1 mark)

b.      If R1= 2ohms, R2= 4ohms and R3 = 6ohms, determine the current flowing in the given circuit. How the value of the current will change if a resistance of 10ohms is connected in series with the circuit.

Ans) Correct identification of Kirchoff’s second rule         (01 mark)

Correct symbol of voltages (+ve/ -ve)              (01 mark)

Correct answer with unit  i.e I= 0.5 A                        (01 mark)

The current remains the same in series circuit (01 mark)

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Students are advised to check your answers.