2009 - JAMB Physics Past Questions and Answers - page 2

When a pentavalent (5 outer electron)atom is added to a pure semiconductor, there is an extra electrons which does not take part in the covalent bonding resulting in an n-type semiconductor.

F ∝	M1M2
__r2

=> F =	GM1M2
__r2

where F is the force of attraction
M₁ and M₂ are masses of the two bodies, r is the distance between them, and G is the universal gravitational constant

∴ G =	_Fr2
M1M2

∴ dimension for force, F =	ML	= MLT-2
T.T

The dimension for G =	MLT-2L2	=	L3T-2
_MM	_M

= M^-1L³T^-2
In comparison with M^xL^yT^z, the values for x, y and z = -1, 3, -2

R² = 100² + 60²
10000 + 3600 = 13600
R = √13600 = 117km
60kml & = tan = ⁶⁰/₁₀₀
tan^-1 0.6
= 31^o west of the North
117km N31^ow

From S = ut + ¹/₂ at²
S = ¹/₂ ut², since U = 0
Let S₅ = distance in 5 seconds
= ¹/₂ x 4 x 5² = 2 x 25 = 50m
S₄ = distance covered in 4 seconds
= ¹/₂ x 4 x 4² = 2 x 16 = 32m
Distance covered in the fifth second
S₅ - S₄ = 50m - 32m = 18m

Sum of momentum before collision
M₁ U₁ + M₂M₂
12 x 4.2 + 18 x 0
12 x 4.2
= 50.4
Sum of momentum after collision
(m₁ + m₂)v
= (12 + 18)v
= 30v
V = ^50.4/₃₀
= 1.7ms^-1

At vt = terminal velocity
= zero acceleration
= uniform velocity

PV = nRT

∴ P =	nRT	=	2 x 8.313 x 300
_V	___10-2

= 4.987 x 10⁵ Nm^-2

Diffraction is spreading of wave after passing through a slit

F = Ke (Hooks law)
K = ^F/_e = ⁸⁰/₄
= 20 Nm^-1

f = c/λ

∴ f =	c	=	3 x 108
λ	500 x 109

=6.0 x 10¹⁴ Hz