Physics 2nd year Chapter 17 important questions test

                          Academy  For  Excellence  Chung lahore

          Test –physics               2^nd year                                  Total  No # 20

Q#1  Choose the correct answer from the followings.      (5)

A substance that undergoes a temporary deformation is called

          (a) ductile             (b) brittle              (c) ceramic            (d) organic

Conductivity of insulator is of the order of

          (a) 107(W-m)-1               (b) 10-6 to 10-4 (W-m)-1

          (c) 10-10 to 10-20 (W-m)-1       (d) infinite

A doped semi conductor is called

          (a) P type              (b) N type             (c) extrinsic           (d) intrinsic

On increasing the temperature of a semiconductor

          (a) the number of charge carriers will increase

          (b) the number of charge carriers will decrease

          (c) the average drift speed will increase

          (d) the resistance of the semiconductor will increase

A permanent magnet must have

          (a) high retentivity                   (b) low retentivity

          (c) low coercive force      (d) low Curie's temperature

Q#2     SHORT QUESTIONS                      (8)

1.       Write the difference between crystalline and amorphous solids.

2.       What are the paramagnetic and ferromagnetic materials?

3.       Describe the graph of the ductile materials.

4.       What is the strain energy?

Q#3     LONG QUESTIONS                        (7)

Write a note on hysteresis loop.

A wire 2.5 m long and cross area is 10^-5 m²  stretched  1.5 mm by a force of 100 N in the elastic region. Calculate (1) the strain (2) Young Modulus (3) The energy store in the wire.