The process of increasing the energy of an atom via inelastic collision with an electron is known as
Aionization
Bexcitation
Cfield emission
Dphotoemission
Ethermonic emission
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Question 662
waec1998
The diagram above represents a section of a pair of vernier calipers. The reading on the instrument is
A5.22cm
B5.24cm
C5.26
D5.35
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Question 663
waec1998
When light from a source is sent through a gas
I. Certain wavelengths are absorbed.
II. an emission line spectrum results.
III. A dark line is left.
Which of the following is/are correct?
Ai only
Biii only
Ci and ii only
Di and iii only
Eii and iii only
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Question 664
waec1998
An electron is accelerated from rest through a potential difference of 70kV in a vacuum. Calculate the maximum speed acquired by the electron (electronic charge = -1.6 x 10-19; mass of an electron = 9.1 x 10-31kg)
A3.00 x 108ms-1
B2.46 x 108ms-1
C1.57 x 108ms-1
D1.32 x 108ms-1
E1.11 x 108ms-1
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Question 665
waec1998
Which of the following explains the concave meniscus of water in a clean glass tube? the
Aadhension between water and glass molecules is greater than the sdhension between water molecules
Bcohension between water molecules is greater then the adhension between glass and water molecule
Cmolecules of water near the glass move faster than the molecules at the centre of the tube
Dmolecules of water at the water-air boundary are often attracted to the centre of the tube
Eweight of the water pulls the centre part of the surface down
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Question 666
waec1998
Use the following data to determine the length L of a wire when a fore of 30N is applied, assuming Hooke's law is obeyed
\(\begin{array}{c|c}\text{Force applied/N} & 0 & 5 & 10 & 30\\ \hline \text{length of wire/mm} & 500.0 & 500.0 & 501.0 & L \end{array}\)
A3.0mm
B3.5mm
C503.00mm
D503.5mm
E506.0mm
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Question 667
waec1998
The diagram below illustrates an a.c.source of 50V(r.m.s.), \(\frac{100}{\pi}\)Hz connected in series with an inductor of inductor of inductance L and a resistor of resistance R. The current in the circuit is 2A and the p.d across L and R are 30V and 40V respectively. Calculate the average power dissipated in the circuit
A100W
B80W
C60W
D20W
E10W
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Question 668
waec1998
The diagram below illustrates an a.c.source of 50V(r.m.s.), \(\frac{100}{\pi}\)Hz connected in series with an inductor of inductor of inductance L and a resistor of resistance R. The current in the circuit is 2A and the p.d across L and R are 30V and 40V respectively. Calculate the power factor of the circuit
A1.33
B1.25
C0.80
D0.75
E0.60
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Question 669
waec1998
The direction of the magnetic field at a point in the vicinity of a bar magnetic is
Aalong the line joining the point to the neutral point
Balways away from the south pole of the magnet
Copposite the direction of theresultant field at that point
Dalways towards the north pole of the magnet
Ethe direction towards which the north pole of a compass needle would point
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Question 670
waec1998
A proton of charge 1.6 x 10\(^{19}\)C is projected into a uniform magnetic field of flux density 5.0 x 10\(^5\)T. If the proton moves parallel to the field with a constant speed of 1.6 x 10\(^6\)ms\(^{-1}\), calculate the magnitude of the force exerted on it by the field
A0.0N
B2.0 x 10-21N
C1.3 x 10-17N
D5.1 x 10-14N
E2.3 x 1013N
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Question 671
waec1998
Lenz's law of electromagnet states that
Athe induced charge is constant for a fixed change of force
Ba force is exerted on a current-carrying conductor in a magnetic field
Cthe magnitude of the induced e.m.f in a circuit is proportional to the rate of change of the number of lines of force linking the circuit
Dthe induced current in a conductor is in such a direction as to oppose the change producing it
Ee.m.f. is induced in a circuit whenever there is a change in the magnetic flux linked with the circuit
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Question 672
waec1998
The diagram above illustrates a freely suspended bar magnet NS hanging from a point in a horizontal ceiling. The thread used for suspending the magnet and the axis of the magnet are as indicated on the diagram. The angle marked \(\theta\) is called the angle os
Adepression
Bdeclination
Cvariation
Delevation
Edip
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Question 673
waec1998
Calculate the resistance of the filament of lamp rated at 240V 60W
A240\(\Omega\)
B360\(\Omega\)
C960\(\Omega\)
D144\(\Omega\)
E2880\(\Omega\)
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Question 674
waec1998
A cell of e.m.f. 1.5v is connected in series with a resistor of 3\(\Omega\). A high resistance voltmeter connected across the cell registers only 0.9v. Calculate the internal resistance of the cell
A5.0\(\Omega\)
B4.5\(\Omega\)
C2.4\(\Omega\)
D2.0\(\Omega\)
E1.8\(\Omega\)
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Question 675
waec1998
In the electrical method of magnetisation, the polarity of the magnet depends on the
Aamount of current passed
Bdirection of current
Cmagnetic material used
Dsize of the magnetic material
Eorientation of the magnetic material in space
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Question 676
waec1998
The gravitational force of the moon is one-sixth that of the earth. If a body weighs 6.0N on the moon. Calculate its weight on the earth
A36.0N
B12.0N
C6.0N
D2.0N
E1.0N
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Question 677
waec1998
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 678
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 679
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 680
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
