A solid of weight 0.600N is totally immersed in oil and water respectively. If the upthrust of oil is 0.210N and the relative density of oil is 0.875. Find the upthrust in water.

• A. 0.600N
• B. 0.360N
• C. 0.240N
• D. 0.180N

The main function of the mouth of a telephone is to convert sound energy into

• A. heat energy
• B. light energy
• C. chemical energy
• D. electrical energy

Which of the following is not a safety precaution in a nuclear station?

• A. Radioactive materials are stored in glass casings
• B. Radioactive materials are handled with remote-controlled tongs
• C. Technicians in nuclear stations wear radio-sensitive badges which are checked regularly.
• D. Radioactive materials are kept in thick-walled lead containers

(a) State the three characteristics of sound and the factor on which each of them depends.

(b) Explain resonance as applied to sound.

(c) What role does echo play in the construction of a concert hall?

(d) The surface of an ear drum (assumed circular) has a radius 2.1 mm. It resonates with an amplitude of 0.8 x 10\(^{-7}\) in as a result of impulses received from an external body vibrating at 2400 Hz. If the resulting pressure change on the ear drum is 3.6 x 10\(^{-5}\) NM\(^{-2}\), calculate the:

(i) period of oscillation;

(ii) velocity;

(iii) acceleration;

(iv) force. [\(\pi\) = 3.14 ].

When light passes through two media x and y of refraction indices 1.51 and 1.33 respectively, the speed of light in

• A) x is same as in y
• B) x and y is same as in vacuum
• C) x is higher than in y
• D) y is higher than in x

The sagging of overhead electrical cables is the consequence of

• A. linear expansivity
• B. . superficial expansivity
• C. cubic expansivity
• D. conductivity

An ammeter of resistance 5Ω has a full-scale deflection when a current of 50 mA flows in it. The value of the resistor required to adapt it to measure a current of 5 A is?

• A) 0.25Ω
• B) 5.00Ω
• C) 19.80Ω
• D) 0.05Ω

Electrons were discovered by

• A. James Chadwick B.
• B. J.J Thompson
• C. Sir Isaac Newton
• D. Charles Newton

(a) (i) Explain (I) electric potential; (II) electric potential energy

(ii) State the SI unit of each of the term in (a)(i) above

(b) An isolated electrically charged sphere of radius, r, and charge, Q, is supported on an insulator in air of permitivity, \(\varepsilon_o\). Write down;

(i) an expression for the electric field intensity on the surface of the sphere;

(ii) an expression for the electric potential at the surface of the sphere;

(iii) a relationship between the electric field intensity and the electric potential at the surface of the sphere

(c) The plates of a parallel plate capacitor, 5.0 x 10\(^{-3}\) m apart are maintained at a potential difference of 5.0 x 10\(^{4}\) V. Calculate the magnitude f the

(i) electric field intensity between the plates

(ii) force on the electron

(iii) acceleration of the elctron

[electronic charge = 1.60 x 10\(^{-19}\)C, mass of electron = 9.1 \times 10\(^{-31}\) kg]

A string of length 1.0 m vibrates in 10 loops. If the total mass of the string is 1.0 x 10^-3 kg and the tension in it is 10N, calculate the frequency of the vibration.

• A. 50Hz
• B. 100Hz
• C. 250Hz
• D. 400Hz