In photoelectric effect, electrons will leave the metal surface when illuminated by light of appropriate frequency if the photon energy is
Agreater than the work function
Bless than the work function
Cequal to the work function
Dequal to the maximium kinetic energy of the electron
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Question 32
jamb1998
In a nuclear fusion experiment, the loss of mass amounts to 1.0 x 10-6kg. The amount of energy obtained from the fusion is
A3.0 x 10-4J
B3.0 x 10-1J
C9.0 x 104J
D9.0 x 1010J
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Question 33
jamb1998
The electrochemical equivalent of a metal is 1.3 x 10-7kgC-1. The mass of the metal which 2.0 x 104C of electricity will deposit from a suitable electrolyte is
A6.5 x 10-2kg
B2.6 x 10-2kg
C6.5 x 10-3kg
D2.6 x 10-3kg
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Question 34
jamb1998
A transformer which can produce 8V from a 240v a.c. supply, has an efficiency of 80%. If the current in the secondary coil is 15A, calculate the current in the primary coil.
A0.625A
B1.600A
C2.500A
D6.250A
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Question 35
jamb1998
Electricity is supplied to a school along a cable of total resistance 0.5\(\Omega\) with the maximum current drawn from the mains as 100A. The maximum energy dissipated as heat for 1 hr is
A3.6 x 103J
B5.0 x 103J
C3.0 x 105J
D1.8 x 107J
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Question 36
jamb1998
The iron core of an induction coil is made from bundles of wire so as to
Aminimize eddy-currents
Bgenerate eddy-current
Cprevent sparking at the contact breaker
Dget the greatest posible secondary voltage
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Question 37
jamb1998
A parallel plate capacitor has a common plate area of 5 x 10\(^{-8}\)m2 and plate separation of 2 x 10\(^{-3}\)m, Assuming free space,
What is the capacitance? [\(\varepsilon\)o = 9.0 X 10-\(^{-12}\)C2N-1m-2]
A2.25 x 10-17F
B4.50 x 10-17F
C2.25 x 10-16F
D4.50 x 10-16F
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Question 38
jamb1998
Find the work done in moving a 2 C charge between two points X and Y in an electric field if the potential difference is 100 volts
A50J
B100J
C200J
D400J
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Question 39
jamb1998
Which of the following can be used to reduce local action in a Laclanche cell?
AA carbon rod as the positive pole
BPure zinc as the negative pole
CPotassium permanganate solution in contact with the positive pole
Dcommon salt solution
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Question 40
jamb1998
An ebonite rod rubbed with fur attracts a glass rod rubbed with silk because
Aebonite has a negative charge while glass has a positive charge
Bebonite has a positive charge while glass has a negative charge
Cboth have negative charges
Dboth have positive charges
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Question 41
jamb1998
The force of repulsion between two point positive charges 5\(\mu\)C and 8\(\mu\)C separated at a distance of 0.02m apart is. [\(\frac{1}{4{\pi}{\varepsilon}_o}\) = 9 x 10\(^9\)Nm\(^2\)C\(^{-2}\)]
A1.8 x 10-10N
B9.0 x 10-8N
C9.0 x 102N
D4.5 x 103N
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Question 42
jamb1998
Which of the following are true about the infra-red radiation? i. it is invisible ii. it is called heat ray iii. its frequency is higher than that of blue light iv. it travels as a transverse wave
Ai, ii, iii and iv
Bi, ii, iv only
Ci, iii, iv only
Dii, iii, iv only
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Question 43
jamb1998
A man wears convex lens glasses of focal length 30cm in order to correct his eye defect. instead of the optimum 25cm, his least distance of distinct vision is
A14cm
B28cm
C75cm
D150cm
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Question 44
jamb1998
The displacement d produced in a glass block of thickness t and refractive index n when an object is viewed through it is
At – n
Bt (1 + 1/n)
Ct (1-1/n)
Dt (1/n - 1)
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Question 45
jamb1998
The most suitable type of mirror used for the construction of the search light is the?
Aconcave mirror
Bconvex mirror
Cspherical mirror
Dparabolic mirror
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Question 46
jamb1998
An object is placed in front of two plane mirrors inclined at an angle of 0o. If the total number of images formed is 7, Find the value of \(\theta\)
A30o
B45o
C51o
D90o
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Question 47
jamb1998
An object 0 lies at a distance m in front of concave mirror of focal length f. If m < f, then the final image obtained will be
Avirtual and diminished
Bmagnified and erect
Creal and inverted
Ddiminished and erect
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Question 48
jamb1998
In a resonance tube experiment, if the fundamental frequency of the vibrating air column is 280Hz, the frequency of the third overtone is
A70Hz
B840Hz
C1120Hz
D1960Hz
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Question 49
jamb1998
A steel wire of length 0.50m is stretched between two fixed points and its fundamental frequency is 200Hz. The speed of the wave in the wire is
A100ms-1
B120ms-1
C200ms-1
D250ms-1
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Question 50
jamb1998
In a closed organ pipe producing a musical note, an antinode will always be produced at
