(a) Explain what is meant by: (i) electric field intensity ; (ii) electric lines of force.
(b) Two similar but opposite point charges -q and +q each of magnitude \(5 \times 10^{-8} C\) are seperated by a distance of 8.0cm in vacuum as shown in the diagram below.
Calculate the magnitude and direction of the resultant electric field intensity E at the point P. Draw the lines of force due to this system of charges. [Take \(\frac{1}{4 \pi \varepsilon _{0}}\)]
(c) 
Calculate the following in the series circuit shown above: (i) reactance of the capacitor ; (ii) impedance of the circuit ; (iii) current through the circuit ; (iv) voltage across the capacitor ; (v) average power used in the circuit.
(a) Explain with the aid of a diagram how a converging lens could be used to : (i) ignite a piece of carbon paper ; (ii) produce an enlarged picture on a screen ; (iii) correct an eye defect.
(b) What is a mechanical wave? Describe with the aid of a diagram, an experiment to show that sound needs a material medium for transmission.
State 3 characteristics of sound and mention the factor on which each depends.
(a) Draw a labelled diagram of a vacuum flask. Explain how its construction minimizes heat exchange with the surroundings.
(b) State Boyle’s law. A thread of mercury of length 15cm is used to trap some air in a capillary tube with uniform cross- sectional area and closed at one end with the tube vertical and the open end uppermost, the length of the trapped air column is 20cm. Calculate the length of the air column when the tube is held:
(i) Horizontally ; (ii) vertically with the open end underneath. [Atmospheric pressure = 76cm Hg]
(c) Explain why it is not advisable to sterilize a clinical thermometer in boiling water at normal atmospheric pressure.
(a) Explain with the aid of a diagram what is meant by the moment of a force about a point.
(b) State the conditions of equilibrium for a number of coplanar parallel forces.
A metre rule is found to balance at the 48cm mark. When a body of mass 60g is suspended at the 6cm mark, the balance point is found to be at the 30cm mark. Calculate:
(i) the mass of the metre rule; (ii) the distance of the balance point from the zero end, if the body were moved to the 13cm mark.
(c) Show that the efficiency E, the force ratio M.A and the velocity ratio V.R of a machine are related by the equation \(E = \frac{M.A}{V.R} \times 100%\)
The efficiency of a machine is 80%. Determine the work done by a person using this machine to raise a load of 200kg through a vertical distance of 3.0m.
[Take g = 10ms\(^{-2}\)]
During the same interval, it is observed that a train travels the same distance as does a lorry. The two vehicles therefore have the same
- A. uniform accelation
- B. instateneous velocity
- C. initial velocity
- D. average speed
- E. average velocity
Two radioactive elements A and B have half-lives of 100 and 50 years respectively. Samples of A and B initially contain equal amounts/number of atoms. What is the ratio of the number of the remaining atoms of A to that of B after 200 years?
- A. 4 : 1
- B. 2 : 1
- C. 1 : 1
- D. 1 : 2
- E. 1 : 4
Which of the following is not an electromagnetic radiation?
- A. X-ray
- B. Radio waves
- C. Sunlight
- D. Sound waves
- E. Infra-red radiation
An electron of charge 1.6 x 1019C is accelerated in vacuum from rest at zero volt towards a plate of 40KV. Calculate the kinetic energy of the electron.
- A. 4 x 10 25J
- B. 4 x 1021 J
- C. 6.4 x 1020 J
- D. 6.4 x 10-15 J
- E. 2.5 x 1020 J
Which of the following is/are not affected by a magnetic field?
I. Neutrons
II. Cathode rays
III. Alpha particles
- A. I only
- B. II only
- C. III only
- D. I & III only
- E. I, II & III
Which of the following is/are not correct about isotopes of an element? The have
- A. the same neutron number
- B. the same proton number
- C. same number of electrons
- D. same chemical properties
- E. different physical poperties.
The unit of inductance is the
- A. farad
- B. henry
- C. hertz
- D. ampere
- E. coulomb
Which of the following explains the concave meniscus of water in a glass tube?
- A. The adhesion between water and glas is greater than the cohesion between water molecules
- B. The cohesion between water molecule is greater than the adhesion between glass and water
- C. The molecules of water in the glass are moving faster than the molecules in the other parts
- D. The molecules of water at the water-air boundary are often attracted to the center of the tube
- E. The weight of the water pulls the central part of the surface down
When sugar at the bottom of a glass of water gradually dissolves, the water level does not change applicably. Which of the following statements best describe this?
- A. Water is suitable solvent for sugar
- B. The sugar and the water have become single solution
- C. The volume of water molecule does not change when sugar dissolves.
- D. Sugar molecule is small than that of water
- E. Water molecules are separated by large spaces between them
Which of the following particles of ray has the highest penetrating power?
- A. Beta particles
- B. Alpha particles
- C. Gamma particles
- D. Electrons
- E. Neutrons
Calculate the resistivity of a wire of length 2m and cross-sectional area 0.004cm2 if the resistance is 3.0 Ω.
- A. 0.0000267Ωcm
- B. 0.006Ωcm
- C. 0.26700Ωcm
- D. 0.27500Ωcm
- E. 0.060000Ωcm
Which of the following statement is not correct about loaded spiral spring?
- A. The extension is proportional to the load applied, provided the elastic limite is not exceeded
- B. If the elsatic limit is not exceeded, the contraction is proportional to the load removed.
- C. Up to the yield limit, extension is no longer proportional to the applied load.
- D. Beyond the elsatic limit, extension is no longer proportional to the applied load.
- E. If the string regains its shape or form after deformation, it is said to be elastic.
What is the effect of using split-rings in a simple d.c motor?
- A. The direction of rotation of the coil is reversed
- B. The current in the coil flows in the same direction
- C. The current in the coil becomes alternating
- D. The direction of the force on the coil is reversed
- E. The contact with the voltage is cut-off
A lamp is marked 220V 60 W. Calculate the energy it would consume when connected to a 220V source for 1 hour.
- A. 216000J
- B. 13200J
- C. 3600J
- D. 864J
- E. 220J
It takes 4 minutes to boil a quantity of water electrically. How long will it take to boil same quantity of water using the same heating coil but with the current doubled? (neglecting any external heat loss).
- A. 64 minutes
- B. 32 minutes
- C. 8 minutes
- D. 2 minutes
- E. 1 minute
Two parallel conductors carry equal currents in the same direction. Which of the following statement is not a correct observation?
- A. Each of teh conductors will experience a force
- B. Each of the conductors can move
- C. The forces on the conductors will be equal
- D. There are concentric lines of force around each conductor
- E. The two conductors will repel each other
A battery of emf 24V and internal resistance 4Ω is connected to a resistor of 32Ω. What is the terminal p.d of the battery?
- A. 24.0V
- B. 21.3V
- C. 16.0V
- D. 2.7V
- E. 2.0V