### Physics Past Questions

61
What optical instrument can best be constructed with converging lenses of focal lengths 50cm and 5cm?
• A. Compound microscope
• B. Galileo's telescope
• C. Terrestrial telescope
• D. Astronomical telescope
JAMB 2000
62
in a pure semiconductor, the number of electrons in the conduction band is
• A. less than the number of holes in the valence band
• B. equal to the number of holes in the valence band
• C. greater than the number of holes in the valence band
• D. twice the number of holes in the valence band
JAMB 2000
63

In a thermonuclear reaction, the total initial mass is 5.02 x $$10^{-{2}{7}}$$kg and the total final mass is 5.01 x $$10^{-{2}{7}}$$kg. The energy released in the process is
[c = 3.0 x $$10^8$$ ms-1]

• A. 9.0 x 10-13J
• B. 9.0 x 10-12J
• C. 9.0 x 10-11J
• D. 9.0 x 10-10J
JAMB 2000
64
A gas would serve as an electrical conductor under
• A. reduced pressure and high current
• B. increased magnetic field
• C. reduced pressure and reduced potential
• D. exposure to visible light
JAMB 2000
65
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 = ∞
JAMB 1999