Physics (Essay) Paper 2 WASSCE (PC), 2022

Question 12

 

(a)  Define  each of the following terms as applied to the structure of the atom:
(i)   isotopes;
(ii)  isobars.
(b)    A lead sphere of mass 5.0 x 10-3kg is allowed to fall to the ground from a height of 20.0 m. Determine the:

(i)  speed of the sphere just before it hits the ground;

(ii) deBroglie wavelength of the sphere just before it hits the ground.[ g = 10.0 m s-2; h = 6.63 x 10-34J s]

(c)        An electron is accelerated in an X-ray tube with a supply of 100 kV accelerating potential. Calculate the:

(i)         speed of the electron;

(ii)        wavelength of the x-ray that will be produced when the electron is suddenly Stopped by a solid metal placed on its path.[ h = 6.63 x 10-34J s, e =  1.6 x 10-19 C, Me = 9.1 x 10-31 kg ]

Observation

 

The expected response:

  • (a)        Definition of terms
  • (i)         Isotopes : Atoms of the same element with the same proton/atomic number but different neutron/mass number.                     

(ii)        Isobars : Atoms of different elements with the same nucleon/mass number but different proton/atomic number.