1999 - JAMB Physics Past Questions and Answers - page 4
31
A semiconductor diode is used in rectifying alternating current into direct current mainly because it
A
allows current to flow in either direction
B
is non-linear
C
offers a high input resistance
D
allows current to flow only in one direction
correct option: d
A rectifier of an alternating current is a device which allows the flow of current only in one direction
Users' Answers & Comments32
if ∆x is the uncertainty in the measurement of the position of a particle along the x-axis and ∆Px is the uncertainty in the measurement of the linear momentum along the x-axis, then the uncertainty principle relation is given as
A
∆x ∆Px ≥ h
B
∆x ∆Px = 0
C
∆x ∆Px < h
D
∆x ∆Px = ∞
correct option: a
Users' Answers & Comments33
If ∆x is the uncertainty in the measurement of the position of a particle along the x-axis and ∆Pa is the uncertainty in the measurement of the linear momentum along the x-axis, then the uncertainty principle relation is given as
A
∆x ∆Px ≥ h
B
∆x ∆Px = 0
C
∆x ∆Px < h
D
∆x ∆Px = ∞
correct option: a
Users' Answers & Comments34
A
8.0 ms-2, 4,0 ms-2
B
4.0 ms-2, 8.0 ms-2
C
4.0 ms-2, 2.0 ms-2
D
2.0 ms-2, 4.0 ms-2
correct option: c
Acceleration = slope = AE/OE = 80/20 = 4m/s2
∴ acceleration and retardation = 4m/s2; 2m/s2
Users' Answers & Comments∴ acceleration and retardation = 4m/s2; 2m/s2
35
A
13.3N
B
20.0N
C
40.0N
D
80.0N
correct option: c
Since P1 is frictionless and P2 as shown is simply used as a hook for the effort, the weight W = 40N
Users' Answers & Comments36
A
The solid will fall over if the vertical line through G lies outside the base
B
The solid will fall over if the vertical line through lies inside the base
C
The solid will not fall over if the vertical line through G lies outside the base
D
The solid can never fall over
correct option: a
The solid will fall over if when the vertical line through G lies outside the base, when slightly tilted
Users' Answers & Comments37
A
both valves are open
B
P is open while Q is closed
C
P is closed while Q is open
D
Both valves are closed
correct option: b
Users' Answers & Comments38
A
15 cm3
B
25 cm3
C
35 cm3
D
45 cm3
correct option: b
Since the temperature of the air is to remain Constant => P1V1 = P2V2
∴ 75 x 30 = (75 + 15) x V2
75 x 30 = 90 x V2
= 25cm2
Users' Answers & Comments∴ 75 x 30 = (75 + 15) x V2
75 x 30 = 90 x V2
| => V2 = | 75 x 30 |
| _90 |
| = | 2250 |
| _90 |
= 25cm2
39
A
3.0 x 107Hz
B
9.0 x 107Hz
C
1.0 x 109Hz
D
3.0 x 109Hz
correct option: d
The frequency f = V/λ,
Where λ = wavelength
From the above, the distance OA = one wavelength; AB = one wave length and BC = one wavelength.
=> OC = 3 wavelength = 3λ
∴3λ = 0.3M
λ = 0.3/3
= 0.1m
∴ f = V/λ = (3.0 x 108) / 0.1
= 3.0 x 109Hz
Users' Answers & CommentsWhere λ = wavelength
From the above, the distance OA = one wavelength; AB = one wave length and BC = one wavelength.
=> OC = 3 wavelength = 3λ
∴3λ = 0.3M
λ = 0.3/3
= 0.1m
∴ f = V/λ = (3.0 x 108) / 0.1
= 3.0 x 109Hz
40
A
binocular
B
spectrometer
C
periscope
D
projector
correct option: c
Users' Answers & Comments