An electromagnetic wave of frequency 5.0 x 1014Hz, is incident on the surface of water of refractive index \(\frac{4}{3}\). Taking the speed of the wave in air as 3.0 x 108ms-1, calculate the wavelength of the wave in water.
A2.2 x 10-6m
B1.7 x 10-7m
C8.0 x 10-7m
D6.0 x 10-7m
E4.5 x 10-7m
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Question 12
waec1998
Which of the following are both mechanical and transverse?
Ainfra-red rays
Bgamma rays
Csound waves
Dwater waves
Emicro waves
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Question 13
waec1998
Calculate he wavelength of a note which is one octave lower than a note of 256Hz in a medium in which the speed of sound is 352ms-1
A0.69m
B1.38m
C2.75m
D5.50m
E9.30m
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Question 14
waec1998
A sonometer wire under a tension of N10N, produces a frequency of 250Hz when plucked. Keeping the length of the wire constant, the tension is adjusted to produce a new frequency of 350Hz. Calculate the new tension
A39.2N
B19.6N
C14.2N
D7.4N
E5.1N
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Question 15
waec1998
the shortest length of the air column in a resonance tube at resonance is 0.12m and the next resonance length is 0.37m. calculate the frequency of vibration given that the speed of sound in air is 340m-1
A1360Hz
B694Hz
C680Hz
D34Hz
E340Hz
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Question 16
waec1998
The intensity of light falling on the film in a camera depend on the i. brightness of the object. ii. diameter of the aperture stop. iii. speed of the shutter. Which of the statements is/are correct/
Ai, ii and iii
Bi and iii only
Ci and ii only
Dii and iii only
Eiii only
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Question 17
waec1998
A lantern gives an image of 3m square of a slide 7.62cm square on a screen. If the screen is 10m from the projection lens of the lantern, calculate the focal length of the lens
A40.3cm
B26.1cm
C24.8cm
D0.7cm
E0.3cm
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Question 18
waec1998
An astronomical telescope having an objective of focal length 100cm and an eyepiece of focal length 10cm is used in normal adjustment, calculate the separation of the lenses
A0.10m
B0.90cm
C1.10m
D1.80m
E2.20m
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Question 19
waec1998
A converging lens of focal length 5cm is used as a magnifying glass by a man whose nearpoint is 35cm. Calculate the magnification given by the lens
A8
B7
C6
D5
E4
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Question 20
waec1998
The images formed by diverging lenses are always
Adiminished, virtual and inverted
Bdiminished, virtual and errect
Cdiminished inverted and real
Dmagnidied, virtual and errect
Emagnified, real and inverted
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Question 21
waec1998
What is the image distance of an object placed at a distance of 2f from a converging lens of focal length f?
Af/4
Bf/2
Cf
D2f
E4f
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Question 22
waec1998
The phenomenon which occurs when light changes direction as it passes from one medium to another is called
Areflection
Bpolarisation
Cinterference
Ddiffraction
Erefraction
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Question 23
waec1998
An eclipse of the sun by the moon occurs when the sun, the moon and the earth are in a straight line and the
Aearth casts a shadow on the moon
Bmoon casts a shadow on the sun
Cmoon is between the sun and the earth
Dearth is between the sun and the moon
Esun is between the moon and the earth
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Question 24
waec1998
If an ebonite rod is rubbed with fur
Aboth the ebonite rod and the fur will be negatively charged
Bthe ebonite rod will be positively charged while the fur will have no charge
Cthere will be electron transfer only if the ebonite rod is earthed
Dthe ebonite rod will be negatively charged while the fur will be positively charged
Ethe ebonite rod will be positively charged while the fur will be negatively charged
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Question 25
waec1998
A 90-W immersion heater is used to supply energy for five minutes. The energy supplied is used to completely melt 180g of a solid at is melting point. Neglecting energy losses to the surroundings, calculate the specific latent heat of fusion of the solid
A0.5Jg-1
B2.5Jg-1
C15.0Jg-1
D450.0Jg-1
E150Jg-1
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Question 26
waec1998
A piece of metal is heated until it becomes red-hot, it is then quickly transferred into a beaker containing boiling water. What effect will this have on the boiling water?
Athe boiling water rises slightly
Bthe boiling point rises sharply
Cthe rate of vaporisation of the boiling water increases
Dthe boiling point first rises and then falls
Eneither the boiling point nor the rate of vaporisation increases
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Question 27
waec1998
A waterfall is 1260m high. Calculate the change in temperature of a quantity of water that falls from the top to the bottom of the waterfall. (Neglect heat losses to the surroundings, take g as 10m-2 and specific heat capacity of water as 4200Jkg-1K-1)
A0.3oC
B3.0oC
C33.3oC
D42.0oC
E100.0oC
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Question 28
waec1998
Dry oxygen is trapped by a pellet of mercury in a uniform capillary tube which is sealed at one end. The length of the column of oxygen at 27oC is 50cm. if the pressure of the oxygen is constant, at what temperature will the length be 60cm?
A360.0oC
B240.6oC
C237.0oC
D87.0oC
E36oC
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Question 29
waec1998
The inside of a vacuum flak is usually coated with silver to reduce heat loss by
Aevaporation
Bradiation
Cconduction
Dconvention
Econdensation
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Question 30
waec1998
Air at temperature 527oC and pressure 30 atmospheres is admitted into the cylinder of an engine. Calculate the pressure of the gas when it has expanded to 5 times its volume and cooled to 127oC as it leaves the engine
