The count rate of a radioactive material is 800 count/min. If the half-life of the material is 4 days, what would the count rate be in 16 days later

• A. 200 count / min
• B. 100 count / min
• C. 50 count / min
• D. 25 count / min

In flemings right-hand rule, the thumb, the forefinger and the middle finger if held mutually at right angles represent respectively, the

• A. motion, the field and the induced current
• B. induced current, the motion and the field
• C. field, the induced current and the motion
• D. induced current, the field and the motion

(a)(i) What is a wave motion?

(ii) State two differences between a radio wave and a sound wave.

(b)(i) Given that you are provided with a tuning fork, a burette and other necessary apparatus, describe with the aid of a diagram, an experiment to determine the frequency of a note emitted by a source of sound. [assume the velocity of sound in air is known]

(ii)State two precautions necessary to obtain accurate result in the experiment described in (b)(i) above

(c) A pipe closed at one end is 100 cm long. If the air in the pipe is set into vibration and a fundamental note is produced, calculate the frequency of the note. [ velocity of sound in air = 340 ms\(^{-1}\)]

The mercury column in the barometer at notational atmospheric pressure has a height of?

• A. 0.76 cm at see level
• B. 760 cm at sea level
• C. 7.6 cm at sea level
• D. 76 cm at sea level

Two forces of magnitudes 7N and 3N act at right angles to each other. The angle \(\theta\) between the resultant and the 7N force is given by

• A. cos\(\theta\) = \(\frac{3}{7}\)
• B. sin\(\theta\) = \(\frac{3}{7}\)
• C. tan\(\theta\) = \(\frac{3}{7}\)
• D. cot\(\theta\) = \(\frac{3}{7}\)

The magnetic relay is a device used for

• A. timing in sports
• B. storing magnetic field
• C. reading the magnitude of magnetic flux
• D. controlling another circuit carrying larger current

Which of the following statements is/are correct? I. Pure water freezes at 0°C under normal pressure ll. Water has its highest density at 4°C. III. The volume at 4°C,

• A. I only
• B. II only
• C. I and II only
• D. I and III only

The theory of electronic conduction in solids, which satisfactorily explains the properties of conductors, insulators and semi-conductor, is?

• A) string theory
• B) particle theory
• C) group theory
• D) band theory

An iron rod of length 50m and at a temperature of 60^oC is heated to 70^oC. Calculate its new length. (Linear expansivity of iron = 1.2 x 10^-5K^-1)

• A. 50.006m
• B. 50.060m
• C. 51.600m
• D. 51.200m

A man hears his echo from a nearby hill 2s after he shouted. If the frequency of his voice is 260Hz and the wavelength is 1.29m, how far away is the hill?

• A. 330.0m
• B. 335.4m
• C. 660.0m
• D. 670.8m