DIR Return Create A Forum - Home
---------------------------------------------------------
Examwizardss
HTML https://examwizardss.createaforum.com
---------------------------------------------------------
*****************************************************
DIR Return to: O'level Exams
*****************************************************
#Post#: 266--------------------------------------------------
Re: 100% CORRECT FREE WAEC GCE PHYSICS OBJECTIVE AND ESSAY ANSWE
RS
By: Ebenezer Date: September 12, 2013, 10:14 am
---------------------------------------------------------
(15c)
Given,
wavelength = 5.0*10^-7m = 7.0*10^-7m
i. Blue light has a greater number of electrons
because it has a shorter wavelenght
ii. red light has higher maximum kinetic energy
because it was first deflected
(15di)
Given
Wo = 2.0eV,
wavelenght= 5.0*10^-7m
i. Wo = hf,
Wo= 2*1.6*10^-19 =3.2*10^-19J
3.2*10^-19 = 6.6 *10^-34*Fo
Fo = (3.2*10^-19 )/ (6.6*10^-34) =
0.48*10^-19+34
fo= 0.48*10^15
fo= 4.8*10^14Hz
3.0*10^8 = 4.8*10^14*wavelenght
wavelenght = 3.0*10^8/ 4.8*10^14 =
0.625*10^-6
wavelenght = 6.25*10^-7
(15dii.)
1/2mV^2 = hf - hfo
Kinetic energy = E-Wo
E = hc/wavelenght = (6.6 * 10^-34*3.0*10^ /
5.0*10^-7
E = 19.8 *10^-26 / 5.0*10^-7
E = 3.96 * 10-19J
Kinetic energy = 3.96* 10^-19 - 3.2*10^-19J
= 0.76* 10^-19J
=7.6 *10^-20J
(5)
Young's Modulus = Tensile stress/ Tensile strain
F=mg = 11.0*10=110N
lenght(L)= 2m, d=2mm=0.002m
E = (F/A) / (e/L) = F/A * L/e
E = FL/ Ae
7.0*10^11 = 110*2/A*e
Area(A) = pie d^2 / 4 = 3.142*0.002^2 /4
A =(1.2568 *10^-5 )/4
A= 3.142 * 10^-6m^2
7.0 * 10^11 = 110*2/3.142*10^-6*e
7.0 * 10^11 * 3.142* 10^-6*e = 110*2
2,199,400e =220
e= 220/2,199,400
= 9.1*10^-5m
*****************************************************