61.The current through a resistor in an a.c circuit is given as 2 sin wt. Determine the d.c equivalent of the current.
- A. A/√2
- B. 2/√A
- C. 2 A
- D. √2A
62.The process of energy production in the sun is
- A. nuclear fission
- B. nuclear fusion
- C. electron collision
- D. radioactive decay
63.Energy losses through eddy currents are reduced by using
- A. low resistance wires
- B. insulated soft iron wires
- C. few turns of wires
- D. high resistance wires
64.The inner diameter of a test tube can be measured accurately using a
- A. micrometer screw gauge
- B. pair of dividers
- C. meter rule
- D. pair of vernier calipers
65.A bullet of mass 0.1kg is thrown vertically upwards with a speed of 10ms⁻¹ from the top of a tower 10m high. Neglecting air resistance, its total energy just before hitting the ground is (take g=10ms⁻²)
- A. 5 J
- B. 10 J
- C. 15 J
- D. 20 J
66.A solid weigh 10.00N in air, 6N when fully immersed in water and 7.0N when fully immersed in a liquid X. Calculate the relative density of the liquid X.
- A. 5/3
- B. 4/3
- C. 3/4
- D. 7/10
67.The temperature gradient across a copper rod of thickness 0.02m, maintained at two temperature junctions of 20⁰C and 80⁰C respectively is
- A. 3.0 x 10²Km⁻¹
- B. 3.0 x 10³Km⁻¹
- C. 5.0 x 10³Km⁻¹
- D. 3.0 x 10⁴Km⁻¹
68.If a sound wave goes from a cold region to a hot air region, its wavelength will
- A. increase
- B. decrease
- C. decrease then increase
- D. remain constant
69.Which of the following electromagnetic waves is least energetic?
- A. Infra-red rays
- B. X-rays
- C. Ultra-violet rays
- D. Gamma rays
70.At what frequency would a 10H inductor have a reactance of 2000Ω?
- A. π/2000Hz
- B. π/100Hz
- C. 100/ πHz
- D. 100πHz
71.Gamma rays are produced when
- A. high velocity electrons are abruptly stopped in metals
- B. energy changes occur within the nucleus of atoms
- C. energy changes occur within the electronic structure of atoms
- D. electrons are deflected in very strong magnetic fields
72.What is the speed of a particle of mass 10⁻²⁷kg whose wavelength is 10⁻⁸m? (h = 6.63 x 10⁻³⁴ Js)
- A. 6.63 ms⁻¹
- B. 66.30 ms⁻¹
- C. 663.0 ms⁻¹
- D. 6630.0 ms⁻¹
73.When a ship sails from salt water into fresh water, the fraction of its volume above the water surface will
- A. increase
- B. decrease
- C. remain the same
- D. increase then decrease
74.The velocity ratio of a machine is 5 and its efficiency is 75%. What effort would be needed to lift a load of 150 N with the machine?
- A. 20 N
- B. 30 N
- C. 40 N
- D. 50 N
75.A rope is being used to pull a mass of 10kg vertically upward. Determine the tension in the rope if, starting from rest, the mass acquires a velocity of 4 ms⁻¹ in 8s. (g = 10 ms⁻²)
- A. 5 N
- B. 50 N
- C. 95 N
- D. 40 N
76.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
77.The main reason for making the cover of a vacuum flask airtight is to prevent heat loss by
- A. convection
- B. conduction
- C. radiation
- D. evaporation
78. If a charged ion goes through combined electric and magnetic fields, the resultant emergent velocity of the ion is
79.In a thermonuclear reaction, the total initial mass is 5.02 x 10⁻²⁷kg and the total final mass is 0.01 x 10⁻²⁷kg. The energy released in the process is (c = 3.0 x 10⁸ms⁻¹)
- A. 9.0 x 10⁻¹³J
- B. 9.0 x 10⁻¹²J
- C. 9.0 x 10⁻¹¹J
- D. 9.0 x 10⁻¹⁰J
80.A 2H inductor has negligible resistance and is connected to a 50/π Hz A.C supply. The reactance of the conductor is
- A. 200 Ω
- B. 50 Ω
- C. 100/π Ω
- D. 25/π Ω