If a current carrying coil is mounted on a metal frame, the back e.m.f. induced in the coil causes
Ainductance
Beddy currents
Celecro-magnetism
Ddipole moment
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Question 922
jamb1991
To convert an alternating current dynamo into a direct current dynamo, the
Anumber of turns in the coil is increased
Bstrength of the field magnet is increased
Cslip rings are replaced with a split ring commutator
Dcoil is wound on a soft iron armature
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Question 923
jamb1991
An equipment whose power is 1500W and resistance is 375 ohms would draw a current of
A0.10A
B2.00A
C4.00A
D77.5A
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Question 924
jamb1991
Which of the following obeys Ohm's Law?
AGlass
BDiode
CAll electrolytes
DAll metals
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Question 925
jamb1991
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
A899.70\(\Omega\)
B10.00\(\Omega\)
C0.10\(\Omega\)
D0.01\(\Omega\)
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Question 926
jamb1991
The function of the system of granulated carbon mixed with manganese (IV) oxide in a Letanche cell is to
Aincrease the e.m.f. of the cell to 2.0V
Bprevent local action in the cell
Cprevent polarisation in the cell
Dmake the cell black and hence a good radiator
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Question 927
jamb1991
An insulated rod when rubbed with a material acquires
Aa negative charge if it is made of glass and rubbed with silk
Bno charge if it is made of glass and rubbed with fur
Cno charge if it is made of copper and rubbed with silk
Da positive charge if it is made of copper and rubbed with fur
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Question 928
jamb1991
Which of the following statements is CORRECT about the earth's magnetic field?
Athe angle of dip is the angle which a freely suspended magnet makes with the vertical
Bthe angle of declination is the angle between the magnetic meridian and the geographic meridian
Cthe angle of declination is the angle which a magnetic compass makes with the magnetic meridian
Dthe angle of inclination is the difference between the angle of dip and the angle of declination
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Question 929
jamb1991
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
Abeats
Bechoing
Cresonance
Dreverberation
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Question 930
jamb1991
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?
A330.0m
B335.4m
C660.0m
D670.8m
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Question 931
jamb1991
Two tuning forks of frequency 256Hz and 260Hz are sounded close to each other. What is the frequency of the beats produced?
A2Hz
B4Hz
C8Hz
D258Hz
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Question 932
jamb1991
Which of the following correctly, describes the image of an object, 4cm from a diverging lens of focal length 12cm?
AThe image is virtual, 3cm in front of the lens
BThe image is real, 6cm behind the lens
CThe image is virtual, 6cm in front of the lens
DThe image is real, 3cm in front the lens
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Question 933
jamb1991
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
Apass through undeviated
Bpass through the center of curvature after refraction
Cemerge parallel to the principal axis
Dpass through the principal focus after refraction
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Question 934
jamb1991
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?
A3.0cm
B6.0cm
C9.0cm
D16.0cm
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Question 935
jamb1991
When a plane mirror at which a ray is incident is rotated through an angle \( \theta \), the reflected ray will be rotated through
A\(\frac{1}{2}\)\(\theta\)
B\(\theta\)
C2\(\theta\)
D3\(\theta\)
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Question 936
jamb1991
The image in a pin-hole camera is
Aerrect and formed by refraction through a lens
Bvirtual and formed by dispersion
Cerect and gets sharper as the hole becomes larger
Dinverted and formed by the light from each point travelling in a straight line
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Question 937
jamb1991
Which of the following is TRUE of light and sound waves?
Athey both transmit energy
Bthey both need a mediumfor propagation
Cthey are both transverse waves
Dtheir velocities in air are equal
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Question 938
jamb1991
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
A0.14s
B0.43s
C2.32s
D6.97s
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Question 939
jamb1991
A room is heated by means of a charcoal fire, An occupant of the room standing away from the fire is warmed mainly by
Aconvection
Bradiation
Cconduction
Dreflection
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Question 940
jamb1991
The absolute temperature of a perfect gas is proportional to the average
