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Physics
UTME / JAMB 1985
Reflection, Refraction & Dispersion of Light
Solution
An object is placed 15cm in front of a concave mirror of radius 40cm. The image formed
A
virtual and 60cm behind the mirror
B
real and 60cm behind the mirror
C
virtual and at infinity
D
real and at infinity
E
virtual and 40cm from the mirror
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
u = f
Source: Myschool Past Questions Archive (Record #28627)
Physics
UTME / JAMB 1985
Reflection, Refraction & Dispersion of Light
A 45o triangular glass prism can be used as a reflector of light because
A
A refraction never takes place in such a prism
B
the angle of reflection equals the angle of incidence
C
the refractive index of glass is less than 1
D
it is transparent
E
the critival angle angle for glass is less than 45o
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #28628)
Physics
UTME / JAMB 1985
Reflection, Refraction & Dispersion of Light
A convex mirror is used as a driving mirror because i. its image is erect. ii. it has a large field of view. iii. it has a long focal length. Identify the CORRECT statement(s)
A
i andiii only
B
i and ii only
C
ii and iii only
D
i, ii, and iii only
E
i only
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #28630)
Physics
UTME / JAMB 1985
Reflection, Refraction & Dispersion of Light
Solution
Two rays of light from a point below the surface of water are equally inclined to each other at 60o in water. What is the angle between the rays when they emerge into air? (Take the refractive index of water to be \(\frac{4}{3}\))
A
41.8o
B
44.1o
C
60.0o
D
83.6o
E
120.0o
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
\(\frac{4}{3}\) = \(\frac{sin r_1}{sin 30}\) and \(\frac{4}{3}\) = \(\frac{sin r_2}{sin 30}\)
r1 = 41.8o and r2 = 41.8o
angle between them = r1 + r2
= 83.6o
Source: Myschool Past Questions Archive (Record #28634)
Physics
UTME / JAMB 1985
Current Electricity & Electric Circuits
Solution
A charge of one coulomb liberates 0.0033g of copper in an electrolytic process. How long will it take a current of 2A to librate 1.98g of copper in such a process?
A
5 mins
B
30 mins
C
50 mins
D
60 mins
E
120 mins
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
0.0033g = 1 coulomb
1.98gs = 1.98 x 1
= 600 cou.
Q = It
600 = 2 x t
t = 300sec = 5 mins
Source: Myschool Past Questions Archive (Record #28636)
Physics
UTME / JAMB 1985
Electrostatics & Capacitors
Solution
If the distance between two stationary charged particle is doubled, the magnitude of the electro-static force between them will be
A
doubled
B
halved
C
a quarter of its former value
D
unchanged
E
four times the original value
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
F \(\alpha\) \(\frac{1}{d^2}\)
F x d2 = constant
F1 x (d1)2 = F2 x (d2)2
d2 = 2d1
F1 x (d1)2 = F2 x (2d1)2
F2 = \(\frac{1}{4}\)F1
Source: Myschool Past Questions Archive (Record #28639)
Physics
UTME / JAMB 1985
Magnetism, Electromagnetism & AC Circuits
Which of the following methods CANNOT be used to produce a steel magnet? The
A
passing of an electric current through a solenoid
B
repeated stroking of the specimen with a magnet
C
repeated stroking of the specimen in opposite directions with magnets
D
heating of the specimen
E
hammering of the specimen in the earth's magnetic field
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #28640)
Physics
UTME / JAMB 1985
Current Electricity & Electric Circuits
Solution
A cell gives a current of 0.15A through a resistance of 8\(\Omega\) and 0.3A. When the resistance is changed to 3\(\Omega\) the internal resistance of the cell is
A
0.05\(\Omega\)
B
1.00\(\Omega\)
C
1.50\(\Omega\)
D
2.00\(\Omega\)
E
2.50\(\Omega\)
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
The E.M.F of a circuit is given by
\(E=I(R+r)\)
Hence, E = 0.15(8+r) = 0.3(3+r)
1.2 + 0.15r = 0.9 + 0.3r
1.2 - 0.9 = 0.3r - 0.15r
0.3 = 0.15r
r = \(\frac{0.3}{0.15}\)
r = 2\(\Omega\)
Source: Myschool Past Questions Archive (Record #28641)
Physics
UTME / JAMB 1985
Current Electricity & Electric Circuits
Which of the following will convert a milliammeter to a voltmeter?
A
low series resistance
B
low parallel resistance
C
high series resistance
D
high parallel resistance
E
parallel resistance equal to milliammeter resistance
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #28642)
Physics
UTME / JAMB 1985
Atomic, Quantum, Nuclear Physics & Electronics
Solution
A wire P has half the diameter and half the length of a wire Q of similar material. The ratio of the resistance of P to that of Q is
A
8 : 1
B
4 : 1
C
2 : 1
D
1 : 1
E
1 : 4
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Resistance \(\alpha\) \(\frac{length}{area}\)
\(\frac{R_Q}{R_P}\) = \(\frac{L_QA_P}{L_PA_Q}\)
LQ = 2LP
DQ = 2DP
AP = \(\pi\)\(\frac{(2D_P)^2}{2}\)
= \(\pi\)DP
AQ = \(\pi\)\(\frac{(D_P)^2}{2}\)
= \(\frac{1}{4}\)\(\pi\)DP
therefore, \(\frac{R_Q}{R_P}\) = \(\frac{2L_P \times \pi D_P}{L_P \times \frac{1}{4} \pi D_P}\)
= 2 : 1
Source: Myschool Past Questions Archive (Record #28648)
Physics
UTME / JAMB 1985
Current Electricity & Electric Circuits
Solution
An electric kettle, connected to a 240V mains, produces 6.0 x 105J of heat energy to boil a quantity of water in 5 minutes. Find the resistance of the kettle.
A
14.4\(\Omega\)
B
28.8\(\Omega\)
C
144\(\Omega\)
D
288\(\Omega\)
E
2880\(\Omega\)
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Heat energy = Electrical energy
6 x 105 = \(\frac{V^2}{R}\)t
R = \(\frac{240 \times 240 \times 5 \times 60}{6 \times 105}\)
= 28.8\(\Omega\)
Source: Myschool Past Questions Archive (Record #28649)
Physics
UTME / JAMB 1985
Magnetism, Electromagnetism & AC Circuits
Solution
On which of the following does the operation of a moving coil ammeter depend? i. Electromagnetic induction ii. Force on a carrying-current conductor iii. Magnetic effect of an electric current
A
i only
B
ii only
C
iii only
D
ii and iii only
E
i,ii and iii
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
A moving coil ammeter operates based on the torque produced when current flows through a coil in a magnetic field, which stems from the force on a current-carrying conductor and the magnetic field generated by the electric current itself.
Source: Myschool Past Questions Archive (Record #28650)
Physics
UTME / JAMB 1985
Lenses & Optical Instruments
Which of the following statements is NOT correct?
A
The average range of distinct vision for a normal eye is from the far distance (infinity) up to about 25cm in front of the eye
B
Longsighted people have difficulty in making the eye lense sufficiently powerful to focus on nearby objects
C
Shortsighted people cannot accommodate distant objects
D
Longsighted people need diverging spectacle lenses
E
A person with long sight has his eye-ball too short and the image of an object is therefore formed behind the retina
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #28651)
Physics
UTME / JAMB 1985
Magnetism, Electromagnetism & AC Circuits
Solution
A transformer has a primary coil with 500 turns and a secondary coil with 2500 turns. When the voltage input to the primary coil is 120V, the output is
A
6000V
B
600V
C
240V
D
60V
E
24V
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
For transformers, \(\frac{V_p}{V_s}\) = \(\frac{N_p}{N_s}\) = \(\frac{I_p}{I_s}\)
\(\frac{500}{2500}\) = \(\frac{120}{V_s}\)
Vs = 600v
Source: Myschool Past Questions Archive (Record #28655)
Physics
UTME / JAMB 1985
Current Electricity & Electric Circuits
Which of the following statements about electrolysis is NOT correct?
A
The substances in solution in the electrolyte become ionized
B
Ions are electrically charged and are attracted towards electrodes when a potential difference is applied
C
Ions may be discharged at the electrodes, forming bubbles or deposits
D
The mass deposited depends upon the length of time for which current flows
E
The mass of gas set free or metal deposited is proportional to the square of the current
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #28656)