### Physics Past Questions

46

I. The frictional force is independent of the area of the surfaces in conduct
II. The frictional force depends on the nature of the surfaces in contact
III. The frictional force depends on the speed of sliding
IV. The frictional force is directly proportional to the normal reaction.

Which combination of the above is true of sliding friction?

• A. I, III and IV
• B. I, II and IV
• C. I, II and III
• D. II, III and IV
JAMB 2000
47

Total internal reflection occurs when light moves from?

• A. a dense medium to a less dense medium
• B. air to water
• C. water to glass
• D. a less dense to a dense medium
JAMB 2000
48
A quantity of water at 0°C is heated to about 30°C. At each degree rise in temperature, its density will
• A. rise steadily
• B. fall steadily
• C. fall then rise
• D. rise then fall
JAMB 2000
49
I. Coherence
II. Same frequency
III. Same wavelength
IV. Same Intensity

Which of the conditions above are necessary to produce interference fringes?
• A. I and III
• B. I, II and IV
• C. I, II and III
• D. II and III
JAMB 2000
50
A boy observes a piece of stone at the bottom of a river 6.0m deep. If he looks from the surface of the river, what is the apparent distance of the stone from him? [Refractive Index of Water = 4/3]
• A. 8.0m
• B. 5.5m
• C. 5.0m
• D. 4.5m
JAMB 2000