JAMB - Physics (1991)

• 1

  Which of the following is the most suitable for use as an altimeter?

  回答

  (D)

  An aneroid barometer
• 2

  A body of weight W N rest on a smooth plane inclined at an angle\(\theta\)^o to the horizontal. What is the resolved part of the weight in Newtons along the plane?

  回答

  (A)

  W sin\(\theta\)
• 3

  A small metal ball thrown vertically upwards from the top of a tower with an initial velocity of 20ms-1. If the ball took a total of 6s to reach ground level, determine the height of the tower [g = 10ms-2]

  回答

  (A)

  60m
• 4

  An object moves with uniform speed round a circle. Its acceleration has

  回答

  (B)

  constant magnitude and varying direction
• 5

  A body of mass 100g moving with a velocity of 10.0ms-1 collides with a wall. If after collision, it moves with a velocity of 2.0ms-1 in the opposite direction, calculate the change in momentum.

  回答

  (B)

  1.2Ns
• 6

  A spring of force constant 1500Nm^-1 is acted upon by a constant force of 75N. Calculate the potential energy stored in the string

  回答

  (A)

  1.9J
• 7

  A wheel and axle have radii 80cm and 10cm respectively. If the efficiency of the machine is 0.85, an applied force of 1200N to the wheel will raise a load of

  回答

  (C)

  8160N
• 8

  A 20kg mass is to be pulled up a slope inclined at 30^o to the horizontal. If the efficiency of the plane is 75%, the force required to pull the load up the plane is [g = 10ms^-2]

  回答

  (C)

  133.3N
• 9

  The spiral spring of a spring balance is 25.0cm long when 5N hangs on it and 30cm long, when the weight is 10N. What is the length of the spring if the weight is 3N assuming Hooke's law is obeyed?

  回答

  (D)

  23.0cm
• 10

  The mass of a stone is 15.0g when completely immersed in water and 10.0g when completely immersed in a liquid of relative density 2.0. The mass of the stone in air is

  回答

  (C)

  20.0g
• 11

  A pilot records the atmospheric pressure outside its plane as 63cm of Hg while a ground observer records a reading of 75cm of Hg for the atmospheric pressure on the ground. Assuming that the density of the atmosphere is constant, calculate the height of the plane above the ground. (Relative density of Hg = 13.0 and that of air = 0.00013)

  回答

  (A)

  1200m
• 12

  In which of the following is surface tension important?

  回答

  (B)

  the floating of a dry needle in water
• 13

  A thermometer with an arbitrary scale S, of equal division registers -30^oS at the ice point and +90^oS at the steam point. Calculate the Celsius temperature corresponding to 60^oS

  回答

  (D)

  75.0^oC
• 14

  A brass rod is 2m long at a certain temperature. What is the length for a temperature rise of 100K, if the expansivity of brass is 18 x 10^-6K^-1?

  回答

  (A)

  2.0036m
• 15

  What is the difference in the amount of heat given out by 4kg of steam and 4kg of water when both are cooled from 100ºC to 80ºC? [the specific latent heat of steam is 2,260,000Jkg\(^{-1}\), specific heat capacity of water is 4200Jkg\(^{-1}\)K\(^{-1}\)]

  回答

  (C)

  9,040,000J
• 16

  How long does it take a 750W heater to raise the temperature of 1kg of water from 20^oC to 50^oC [specific heat capacity of water = 4200Jkg^-1K^-1]

  回答

  (C)

  168s
• 17

  The saturated vapour pressure of a liquid increases as the

  回答

  (C)

  temperature of the liquid increases
• 18

  The absolute temperature of a perfect gas is proportional to the average

  回答

  (C)

  kinetic energy of the molecules
• 19

  A room is heated by means of a charcoal fire, An occupant of the room standing away from the fire is warmed mainly by

  回答

  (B)

  radiation
• 20

  A boy timed 30 oscillations of a certain pendulum thrice and obtained 1min. 10s, 1min. 12s and 1min. 7s respectively.The mean period of oscillation of the pendulum is

  回答

  (C)

  2.32s
• 21

  Which of the following is TRUE of light and sound waves?

  回答

  (A)

  they both transmit energy
• 22

  The image in a pin-hole camera is

  回答

  (D)

  inverted and formed by the light from each point travelling in a straight line
• 23

  When a plane mirror at which a ray is incident is rotated through an angle \( \theta \), the reflected ray will be rotated through

  回答

  (C)

  2\(\theta\)
• 24

  A trough 12.0cm deep is filled with water of refractive index \(\frac{4}{3}\). By how much would a coin at the bottom of the trough appear to be displaced when viewed vertically from above the water surface?

  回答

  (A)

  3.0cm
• 25

  In a ray diagram for a thin converging lens, a ray that is not parallel to the optic axis but passes through the optic center will

  回答

  (A)

  pass through undeviated
• 26

  Which of the following correctly, describes the image of an object, 4cm from a diverging lens of focal length 12cm?

  回答

  (A)

  The image is virtual, 3cm in front of the lens
• 27

  Two tuning forks of frequency 256Hz and 260Hz are sounded close to each other. What is the frequency of the beats produced?

  回答

  (B)

  4Hz
• 28

  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?

  回答

  (B)

  335.4m
• 29

  When the bottom tip of a vibrating tuning fork is held in contact with a wooden box, a louder sound is heard. This phenomenon is known as

  回答

  (C)

  resonance
• 30

  Which of the following statements is CORRECT about the earth's magnetic field?

  回答

  (B)

  the angle of declination is the angle between the magnetic meridian and the geographic meridian
• 31

  An insulated rod when rubbed with a material acquires

  回答

  (B)

  no charge if it is made of glass and rubbed with fur
• 32

  The function of the system of granulated carbon mixed with manganese (IV) oxide in a Letanche cell is to

  回答

  (C)

  prevent polarisation in the cell
• 33

  A moving coil galvanometer of 300\(\Omega\) resistance gives full scale deflection for 1.0mA. The resistance R, of the shunt that is required to convert the galvanometer into a 3.0A ammeter is

  回答

  (C)

  0.10\(\Omega\)
• 34

  Which of the following obeys Ohm's Law?

  回答

  (D)

  All metals
• 35

  An equipment whose power is 1500W and resistance is 375 ohms would draw a current of

  回答

  (B)

  2.00A
• 36

  To convert an alternating current dynamo into a direct current dynamo, the

  回答

  (C)

  slip rings are replaced with a split ring commutator
• 37

  If a current carrying coil is mounted on a metal frame, the back e.m.f. induced in the coil causes

  回答

  (B)

  eddy currents
• 38

  The electrochemical equivalent of platinum is 5.0 x 10^-7kgC^-1 to plate-out 1.0kg of platinum, a current of 100A must be passed through an appropriate vessel for

  回答

  (A)

  5.6 hours
• 39

  which of the following statements are TRUE of isotopes? i. isotopes of an element have the same chemical properties because they have the same number of electrons. ii. isotopes of elements are normally separated using physical properties. iii. isotopes of an element have the same number of protons in their nuclei.

  回答

  (B)

  i and iii only
• 40

  When an atom loses or gains a charge, it becomes

  回答

  (B)

  an ion
• 41

  4g of a radioactive material of half-life 10 days is spilled on a laboratory floor. How long would it take to disintegrate 3.5g of the material?

  回答

  (C)

  30 days
• 42

  In a nuclear fusion process, four protons each of mass Mp were fused to produce a nucleus X of mass Mx. Which of the following equations is CORRECT?

  回答

  (A)

  4M_p > M_x
• 43

  Which of the following are True for \(\alpha\)-decay. i. mass number, decrease by four. ii. Atomic number decreases by two. iii. mass number does not change.

  回答

  (A)

  i and ii only
• 44

  Which of the following phenomena is called photoelectric effect?

  回答

  (C)

  a metal absorbs quanta of light and then emits electrons
• 45

  

  Find the tension T1 in the diagram above if the system is in equilibrium
  
  [G = 10ms^-2]

  回答

  (B)

  100/√3N