An electron moves with a speed of 2.0 x 10\(^6\)ms\(^{-1}\) in a straight line. Calculate the wavelength of the electron wave. [mass of an electron = 9.1 x 10\(^{-31}\) kg][Planck's c x 10\(^{-34}\)Js]
A3.63 x 10-10m
B6.51 x 10-9m
C4.24 x 10-8m
D7.25 x 10-8m
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Question 372
waec2010
Eddy currents can be reduced by
Ausing coil of high resistance
Bwinding the coil on a soft iron core
Ccreating holes in the metal plates
Dusing coil of low resistance
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Question 373
waec2010
The resonant frequency of an a.c circuit is 1000 kHz. If each of the capacitance and inductance in the circuit is reduced by 50%, and no other changes are made, the resonant frequency will become
A250kHz
B750kHz
C1000kHz
D2000kHz
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Question 374
waec2010
The energy, E stored in an inductor of inductance L when current I passes through it is given by the equation
AE = \(\frac{1}{2} LI^2\)
BE = LI2
CE \(\frac{1}{2}LI\)
DE = \(\frac{1}{2} L^2I\)
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Question 375
waec2010
In order to prevent bar magnets from losing their strength, they are stored wih keepers such that the two bars are placed with
Alike poles facing each other and the keepers placed between them
Blike poles facing each other and the keepers placed between them
Cunlike poles facing each other and the keepers placed at their ends
Dunlike poles facing each other and the keepers placed between them
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Question 376
waec2010
Which of the following factors will increase the sensitivity of moving coil meter?
Astrong spring
Blow numbers of turns
Csmall area of coil
Dsoft iron core
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Question 377
waec2010
Which of the following factors does not affect the electric resistance of wire?
Alength
Bmass
Ctemperature
Dcross-sectional area
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Question 378
waec2010
In the wiring of houses, the fuse is connected to the wire coloured
Ablue
Bbrown
Cyellow
Dyellow and green
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Question 379
waec2010
A galvanometer of internal resistance 50\(\Omega\) and full scale deflection of 20 mA is converted into a voltmeter by connecting a resistor of resistance 1950\(\Omega\) in series to it. Calculate the maximum voltage that can be read by the voltmeter
A20V
B30V
C38V
D40V
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Question 380
waec2010
Determine the potential difference. V across the parallel resistors
A2.0V
B2.3V
C3.0V
D0.7V
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Question 381
waec2010
Use the diagram above to calculate the current, I.
A0.60A
B0.97A
C1.03A
D5.00A
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Question 382
waec2010
Capacitors are used in the following devices, except
Awater pumping machines
Bceiling fans
Celectric irons
Dtelevision sets
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Question 383
waec2010
A positively charged glass rod is placed near the cap of a positively charged electroscope. The divergence of the leaf is observed to
Adecrease
Bincrease
Cremain the same
Dincrease and collapse immediately
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Question 384
waec2010
As the air column of length L in an air pipe decreases, the frequency of the sationary wave emitted
Adecreases
Bincreases
Cvaries as L2
Dvaries as \(\sqrt{L}\)
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Question 385
waec2010
The amplitude of a sound wave determines its
Afrequency
Bquality
Cloudness
Dpitch
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Question 386
waec2010
Which of the following electromagnetic wave has the longest wavelength?
Aradio-waves
Bgamma rays
Cinfrared waves
Dultraviolet rays
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Question 387
waec2010
A lens that is thinner at the middle and thicher at the edges is
Adiverging
Bconverging
Cplano-convex
Dconverging meniscus
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Question 388
waec2010
A ray of light travels from air to water. The refeactive index of water is given by the expression
A\(\frac{\text{velocity in water}}{\text{velocity in air}}\)
B\(\frac{\text{sine of angle of refraction}}{\text{sine of angle of incidence}}\)
