11)Permanent magnet can be made from
a) cobalt
b) Aluminium
c) zinc
d) lead
12) Compton effect is associated with
a) positive rays
b) b-rays
c) y-rays
d) X-rays
13) Which of the following particles is unstable
a) proton
b) electron
c) photon
d) neutron
14)Which of the following is not a semiconductor
a) germanium
b) silicon
c) arsenic
d) all of these
15) The resistance of a pn junction in forward bias is
a) zero
b) low
c) high
d) infinite