A sonometer wire of length 100cm under a tension of 10N, has a frequency of 250Hz. Keeping the length of the wire constant, the tension is adjusted to produce a new frequency of 350Hz. The new tension is
A5.1N
B7.1N
C14.0N
D19.6N
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Question 42
jamb1990
An organic pipe closed at one end is 80cm long. Determine the frequency of the fundamental note assuming that the speed of sound in air is 340ms-1
A106Hz
B213Hz
C318Hz
D425Hz
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Question 43
jamb1990
In a resonance tube experiment, the effective length of the air column for the first resonance is 20cm when set into vibration by a tuning fork of frequency 480Hz. Neglecting and effect, the velocity of sound in air is
A96ms-1
B255ms-1
C340ms-1
D384ms-1
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Question 44
jamb1990
When light is incident on an object which is magenta in colour, which of the following colour would be absorbed?
ARed and blue
BGreen only
CRed and green
DRed only
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Question 45
jamb1990
For a short sighted person, light rays from a point on a very distant object is focused
Ain front of the retina
Bon the retina by a converging lens
Cbehind the retina by a diverging lens
Din front of the retina, a distance 2F from the lens
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Question 46
jamb1990
What must be the distance between an object and a converging lens of focal length 20cm to produce an erect image two times the object height?
A20cm
B15cm
C10cm
D5cm
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Question 47
jamb1990
A boy looks at the image of an object in a plane mirror. He observes two images, a main bright one and the other faint. The observed images result from?
Areflection only
Brefraction only
Cdiffraction and interference
Dreflection and refraction
Ereflection and diffraction
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Question 48
jamb1990
An object which is 3cm high is placed vertically 10cm in front of a concave mirror. If this object produces an image 40cm from the mirror, the height of the image is
A0.75cm
B4.00cm
C8.00cm
D12.00cm
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Question 49
jamb1990
Shadows and eclipses result from the
Arefraction of light
Brectilinear propagation of light
Cdefraction of light
Dreflection of light
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Question 50
jamb1990
A wave disturbance travelling in air enters a medium in which its velocity is less than that in air. Which of the following statements is true about the wave medium?
Aboth the frequency of the wave and the wavelength are decreased
Bthe frequency of the wave is decreased while the wavelength is increased
Cthe frequency of the wave is unaltered while the wavelength is decreased
Dthe frequency of the wave is decreased while the wavelength is unaltered
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Question 51
jamb1990
A light wave of frequency 5 x 10\(^{14}\)Hz moves through water which has a refractive index of \(\frac{4}{3}\). Calculate the wavelength in water if the velocity of light in air is 3 x 10\(^8\)ms\(^{-1}\)
A4.5 x 10-7m
B6.0 x 10-7m
C1.7 x 106m
D2.2 x 106m
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Question 52
jamb1990
Which of the following statements are correct? i. land and sea breezes are natural convection currents. ii. convection may occur in liquids or gasses but not in solids. iii. the vacuum in a thermos flask prevents heat loss due to convection only.
Ai and ii only
Bi and iii only
Ci and iii only
Di, ii, and iii
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Question 53
jamb1990
Which of the following conditions will make water boil at a temperature of 100oC when the atmospheric pressure is 750mmHg?
Aincrease the external pressure
Breduce the external pressure
Cheat more rapidly at the same pressure
Dreduce the external pressure by a quarter
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Question 54
jamb1990
1kg of copper is transferred quickly from boiling water to a block of ice. Calculate the mass of ice melted, neglecting heat loss. [specific heat capacity of copper 400Jkg-1K-1 and latent heat of fusion of ice 333 x 103Jkg-1]
A60g
B67g
C120g
D133g
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Question 55
jamb1990
The pressure of a gas when cooled at constant volume will decrease because the molecules
Acollide less frequently with the walls of the container
Bhave the same average kinetic energy
Cbreak up into smaller molecules
Ddecrease in number
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Question 56
jamb1990
A bar of initial length /0 is heated through a temperature change \(\Delta\)t to a new length I. The linear expansivity, a, of the bar is
A\(\frac{/ - /_o}{/ \Delta t}\)
B\(\frac{/ - /_o}{/_o \Delta t}\)
C/o(1 + \(\Delta\) t)
D\(\frac{/ - /_o}{/(1 + \Delta t)}\)
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Question 57
jamb1990
The resistances of platinum wire at the ice and steam points are 0.75 ohm and 1.05 ohm respectively. Determine the temperature at which the resistance of the wire is 0.90 ohm
A43.0oC
B50.0oC
C69.9oC
D87.0oC
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Question 58
jamb1990
40m3 of liquid is mixed with 60m3 of another liquid Q. If the density of P and Q are 1.00kgm-3 and 1.6kgm-3 respectively, what is the density of the mixture?
A0.05kgm-3
B1.25kgm-3
C1.30kgm-3
D1.36kgm-3
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Question 59
jamb1990
What is the length of liquid column in a barometer tube that would support an atmospheric pressure of 102000Nm-2 if the density of the liquid is 2600kgm-3? [g = 10ms-2]
A0.75m
B0.76m
C3.92m
D39.23m
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Question 60
jamb1990
An inclined plane which makes an angle of 30o with the horizontal has a velocity ratio of
