2004 - JAMB Physics Past Questions and Answers - page 4
Pressure = Force / Area = Weight of the man / Area of his feet
=> 2.8 x 103 = Weight of the man / 4 x 10-2
∴ Weight of the man = 2.8 x 103 x 4 x 10-2
= 112N
Users' Answers & CommentsFrom the relation refractive index = Sin ( \left(\frac{A+Dm}{2}\right) )
Where A = refractive angle = 600, Sin( \left(\frac{A}{2}\right) )
( \implies 1.4 = \frac{\text{Sin}\left(\frac{60^0 + Dm}{2}\right)}{\text{Sin}\left(\frac{60}{2}\right)} \
= \frac{\text{Sin}\left(\frac{60 + Dm}{2}\right)}{\text{Sin}30^0} \
= \frac{\text{Sin}\left(\frac{60 + Dm}{2}\right)}{0.5}\
\text{Therefore} 1.4 \times 0.5 = \text{Sin}\left(\frac{60 + Dm}{2}\right) \
\text{Therefore} \left(\frac{60 + D_m}{2}\right)= \text{Sin}^{-1} 0.7000 \
= 44^0 12^1 \
60^0 + D_m = 88^0 24^1 \
D_m = 88^0 24^1 - 60^0 \
= 28^0 24 \
29^0 )
Users' Answers & CommentsE = V + v
where E = emf of cell.
V = terminal p.d
v = loss voltage of the cell.
But from ohm's law V=IR ; v = Iv
( \implies ) lost voltage = V = Ir
= 4 x 0.5
= 2.0v
Users' Answers & CommentsOriginal length = 20m
first new length = 20.01m
first increase in length = 20.01m - 20m = 0.01m
Second new length = 20.05m
second increase in length = 20.05 - 20m = 0.05m
From hooke's law = ( \frac{F_1}{e_1} = \frac{F_2}{e_2} \implies \frac{50}{0.01} = \frac{F_2}{0.05} \
\implies F_2 = \frac{50 \times 0.05}{0.01} = 250N )
Users' Answers & CommentsAverage life / Half life (Tl/2) = ln2/λ = 0.693/10-7
= 0.693 x 107
= 6.93 x 108
Users' Answers & CommentsCurrent (I) in the circuit = V/Z
But z =
√ R2 + (XL - XC)2
=
√ 82 + (16 – 10) 2
=
√ 64 + 36
=
√ 100 = 10Ω
∴ Current (I) = V/Z = 12/10 = 1.2 A
Users' Answers & CommentsTemperature coefficient of resistance is given by
α = | Increase in resistance per oC rise in temp. |
__resistance at 0oC |
And for metals where resistance increase with temperature rise, temperature coefficient of resistance is positive; on the other hand in semi conductors, where resistance decrease with temperature rise, temperature coefficient of resistance is negative.
Users' Answers & Comments