Rainbow is formed when sunlight undergoes
- A. reflection
- B. refraction
- C. dispersion
- D. diffraction
The mechanical advantage of the machine shown above
- A. 7.5
- B. 15.5
- C. 30.0
- D. 60.0
Under which conditions is work done
- A. A man supports a heavy load on his head with hands.
- B. A woman holds a pot of water
- C. A boy climbs onto a table
- D. A man pushes against a stationary petrol tanker
The stress experienced by a wire of diameter \(\frac{\text{y}}{\pi}\)m loaded by a weight y\(^2\)N is
- A. \(\pi\)Nm\(^{-2}\)
- B. 2\(\pi\)Nm\(^{-2}\)
- C. 4\(\pi\)Nm\(^{-2}\)
- D. 8\(\pi\)Nm\(^{-2}\)
A metal sphere is placed on an insulating stand. A negatively charged rod is brought close to it. If the sphere is earthed and the rod is taken away, what will be the charge on the sphere?
- A. The sphere will remain neutral.
- B. The sphere will have a net negative charge.
- C. The sphere will have a net positive charge.
- D. The sphere will become polarized
a. State the function of each of the following parts of a modern x-ray tube: i. heater; ii. high tension source; iii. cooling fins.
b. State one reason for each of the following design features of a modern x-ray tube: i. the glass envelope is highly evacuated; ii. the target is a metal of very high melting point; iii. the cooling fins are located outside the glass envelope.
c. In a nuclear fission reaction, a nuclide \(^{235}U_{92}\) is bombarded with a neutron to produce \(^{93}Kr_{36}\) and \(^{141}Ba_{56}\) with additional neutrons, the energy involved in the process is Q.
[mass of \(^{235}U_{92}\) = 235.044 u, mass of \(^{93}Kr_ {36}\) = 91.898 u, mass of \(^{141}Ba_ {56}\) = 140.914 u,
mass of neutron = 1.009u, 1u = \(1.66 \times 10^{-27}\) kg, c = 3.0 × \(10^8ms^1\)]
i. Write down the balanced nuclear reaction equation for the process.
ii. State with reason whether Q is absorbed or released in the process.
iii. Calculate the value of Q in joules.
ai. Define the electric potential at a point in an electric field.
ii. An uncharged body, A, was charged electrostatically by a test charge, B, using the method of induction and the method of contact. State two differences between the two methods.
b. An important precaution during an electricity experiment is to open the circuit when no readings are being taken. Give two reasons for the stated precaution.
ci. Fig. 11.0 is a circuit diagram in which a coil of inductance, L, and a resistor of resistance, R, are connected to a variable alternating source of frequency, f.
The table shows the square of the impedance, \(Z^2\); corresponding to each value of \(ƒ^2\).
|
\(ƒ^2\)/ \(Hz^2\) |
198.80 | 400.00 | 600.30 | 800.90 | 900.00 |
|
\(Z^2\)/ \(Ω^2\) |
249.60 | 400.00 | 550.30 | 702.30 | 800.90 |
Write down the equation for Z in terms of \(f^2\), \(R^2\), and \(L^2\).
ii. Plot a graph \(Z^2 against \(f^2\) of and use it to determine the values of:
i. L
ii. R
[\(π^2\) = 10]
ai. Why are parabolic mirrors suitable for use in the headlamps of vehicles?
ii. Draw a ray diagram to illustrate the answer in 10(a)(i).
bi. State two applications of echoes.
ii. An observer standing at a point, P, on the same horizontal ground as the foot, H, of a tower, shouts, and 1.20 s later, he hears the echo. He then moved to another point, Q, 40 m from P, and shouted again but the echo was heard after 1.45 s. Calculate the:
I. distance between P and H;
II. speed of sound in air.
ci. Define the term absolute refractive index of a medium.
ii. A piece of coin falls accidentally into a tank containing two immiscible liquids A and B as illustrated in Fig. 10.0 above.
Calculate the displacement of the coin when viewed vertically from above.
[refractive index of A = 1.3, refractive index of B = 1.4]
a. Define each of the following terms used with simple machines:
i. Pivot ii.Load iii. Efficiency.
b. A truck of mass 1.2 × \(10^3\) kg is pulled from rest by a constant horizontal force of 25.2N on a leveled road. If the maximum speed attainable in the process is 60 km/h.
Calculate the: i. work done by the force; ii. distance traveled by the truck in reaching the maximum speed.
c. State two differences between absolute zero temperature and ice point.
d. An uncalibrated liquid-in-glass thermometer was used in determining a Celsius temperature. The readings are tabulated below
| Temperature/°C | -6 | 0 | 100 |
| Length of column/ cm | L | 2.0 | 15.0 |
ai. State the reason why simple harmonic motion is periodic.
ii. State two factors that affect the period of oscillation of a simple pendulum.
iii. Sketch a graph of the total mechanical energy, E, against displacement, y, for the motion of a simple pendulum from one extreme position to the other.
b. The diagram above illustrates an oscillatory pendulum. Calculate the work done in raising the pendulum to point B, if the mass of the bob is 50 g.
[g = \(10 ms^2\)] see the figure above
c. A spiral spring of spring constant, k, and natural length, l, has a scale pan of mass 0.04 kg hanging on its lower end while the upper end is firmly fixed to a support. When an object of mass 0.20 kg is placed on the scale pan, the length of the spring becomes 0.055 m and when the object is replaced with another object of mass 0.28 kg, the length of the spring becomes 0.065 m. Calculate the values of k and l.
[g = \(10 ms^2\)]
a. What is fibre optics?
b. State two reasons why optical fibres are preferred to copper cables in the telecommunication industry.
a. State one difference between an intrinsic and an extrinsic semiconductor.
b. Draw a circuit diagram to illustrate full wave smoothing rectification.
a. Using the kinetic theory, explain the term diffusion of fluid molecules.
b. Name one phenomenon that demonstrates that light behaves as a:
i. wave ii. particles
State three differences between geostationary satellites and polar satellites.
a. A projectile is fired at an angle, θ, to the horizontal with velocity, u. Show that at any time, t, during the motion, the: i. horizontal component of the velocity is independent of t;
ii. vertical component of the velocity depends on t.
b. State the assumption on which projectile motion is based.
a. Define strain energy.
b. Write an expression for the energy stored, E, in a stretched wire of original length, l , cross-sectional area, A, extension, e, and Young’s modulus, Y, of the material of the wire.
The force, F, acting on the wings of an aircraft moving through the air of velocity, v, and density, ρ, is given by the equation F = \(kv^xρ^yA^z\), where k is a dimensionless constant and A is the surface area of the wings of the aircraft. Use dimensional analysis to determine the values of x, y, and z.
The purpose of commutators in a direct current motor is to
- A. reverse the direction of the current after every half rotation
- B. increase the number of rotations per second
- C. enable a uniform couple to act on the coil.
- D. increase the efficiency of the motor.
The conclusive test for magnetism in a steel bar suspended horizontally at its midpoint is when the bar
- A. always settles in the magnetic N-S direction.
- B. is repelled by a magnet.
- C. always settles in the magnetic E-W direction
- D. is attracted by a magnet.
Which of the following devices is associated with alternating currents only?
- A. Step-up transformer
- B. Induction coil
- C. Moving coil galvanometer
- D. Lead-acid accumulator
Which of the following equations is not a correct mirror formula? [The symbols have their usual meanings]
- A. N = \(\frac{360}{\theta}\)
- B. \(\frac{1}{f} = \frac{1}{u} + \frac{1}{v}\)
- C. m = \(\frac{v}{u}\)
- D. f = \(\frac{1}{D}\)