15/06/2022
WAEC PHYSICS SOLUTIONS
========================
(1)
Range /PQ/ = u²sin2θ/g
u = 250ms-¹
θ =42°
= [250² x sin(2x42°)]/10
= (62,500 x sin84°)/10
= 6250 x 0.9945
= 6215.63m
===========================
(2)
(i) They are pure semiconductors with impurities less than 1 and have teravalent crystals
(ii) Presence of mobile charge carriers is intrinsic property of material
(iii) No doping or addition of impurities required.
===========================
(4)
F = 50N
k = 100Nm-¹
F = ke
50 = 100e
e = 50/100 = 0.5m
Work done = (1/2)ke²
= 1/2 x 100 x 0.5²
= 25/2
= 12.5joules
===========================
(5a)
A geostationary satellite is an earth orbiting satellite placed at an altitude of approximately 35,800km directly over the equator that revolves in the same direction which the earth rotates.
(5b)
(i) Gas lasers
(ii) Solid-state lasers
===========================
(7)
(i) Magnetic materials are materials having a magnetic domain and are attracted to an external magnetic field WHILE Non-magnetic materials are materials that are not attracted to an external magnetic field.
(ii) The magnetic domains of magnetic materials are aligned either parallel or antiparallel arrangements thus they can respond to a magnetic field when they are under the influence of an external magnetic field WHILE The magnetic domains of non-magnetic materials are arranged in a random manner in such a way that the magnetic moments of these domains are cancelled out. Thus, they do not respond to a magnetic field.
(iii) Magnetic materials are used to make permanent magnets are the parts of operating systems where magnetic properties are required WHILE Non-magnetic materials are used to make parts of some operating systems where no magnetic effect are expected and other things such as cases of compasses.
More coming....
