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Physics
UTME / JAMB 1990
Elasticity, Density, Pressure & Fluids
Which of the following conditions will make water boil at a temperature of 100oC when the atmospheric pressure is 750mmHg?
A
increase the external pressure
B
reduce the external pressure
C
heat more rapidly at the same pressure
D
reduce the external pressure by a quarter
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #28246)
Physics
UTME / JAMB 1990
Waves, Sound & Vibrations
Solution
A light wave of frequency 5 x 10\(^{14}\)Hz moves through water which has a refractive index of \(\frac{4}{3}\). Calculate the wavelength in water if the velocity of light in air is 3 x 10\(^8\)ms\(^{-1}\)
A
4.5 x 10-7m
B
6.0 x 10-7m
C
1.7 x 106m
D
2.2 x 106m
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Speed of light in a medium is given by: v = \(\frac{\text{c}}{\text{n}}\)
\(\frac{4}{3}\) = \(\frac{3 \times 10^8}{v}\)
v = 2.25 x 10\(^8\)ms\(^{-1}\)
\(\lambda\) = \(\frac{V}{F}\)
= \(\frac{2.25 \times 10^8}{5 \times 10^{14}}\)
\(\lambda\) = 0.45 x 10\(^{-6}\)m = 4.5\times10\(^{−7}\) m
Source: Myschool Past Questions Archive (Record #28250)
Physics
UTME / JAMB 1990
Waves, Sound & Vibrations
A wave disturbance travelling in air enters a medium in which its velocity is less than that in air. Which of the following statements is true about the wave medium?
A
both the frequency of the wave and the wavelength are decreased
B
the frequency of the wave is decreased while the wavelength is increased
C
the frequency of the wave is unaltered while the wavelength is decreased
D
the frequency of the wave is decreased while the wavelength is unaltered
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 #28253)
Physics
UTME / JAMB 1990
Reflection, Refraction & Dispersion of Light
Shadows and eclipses result from the
A
refraction of light
B
rectilinear propagation of light
C
defraction of light
D
reflection of light
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 #28256)
Physics
UTME / JAMB 1990
Reflection, Refraction & Dispersion of Light
Solution
An object which is 3cm high is placed vertically 10cm in front of a concave mirror. If this object produces an image 40cm from the mirror, the height of the image is
A
0.75cm
B
4.00cm
C
8.00cm
D
12.00cm
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
\(\frac{\text {object height}}{\text{image height}}\) = \(\frac{\text {object distance}}{\text{image distance}}\)
\(\frac{3}{\text{image height}}\) = \(\frac{10}{40}\)
Image height = 12cm
Source: Myschool Past Questions Archive (Record #28257)
Physics
UTME / JAMB 1990
Lenses & Optical Instruments
Solution
What must be the distance between an object and a converging lens of focal length 20cm to produce an erect image two times the object height?
A
20cm
B
15cm
C
10cm
D
5cm
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
F = \(\frac{uv}{u + v}\); v = 2u
20 = \(\frac{ux - 2u}{u + (-2u)}\); u = 10cm
Source: Myschool Past Questions Archive (Record #28259)
Physics
UTME / JAMB 1990
Lenses & Optical Instruments
For a short sighted person, light rays from a point on a very distant object is focused
A
in front of the retina
B
on the retina by a converging lens
C
behind the retina by a diverging lens
D
in front of the retina, a distance 2F from the lens
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #28261)
Physics
UTME / JAMB 1990
Current Electricity & Electric Circuits
When light is incident on an object which is magenta in colour, which of the following colour would be absorbed?
A
Red and blue
B
Green only
C
Red and green
D
Red 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 #28263)
Physics
UTME / JAMB 1990
Waves, Sound & Vibrations
Solution
In a resonance tube experiment, the effective length of the air column for the first resonance is 20cm when set into vibration by a tuning fork of frequency 480Hz. Neglecting and effect, the velocity of sound in air is
A
96ms-1
B
255ms-1
C
340ms-1
D
384ms-1
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
\(\lambda\) = 4(L + C) ; where C = o
\(\lambda\) = 4 x 20 = 80cm
V = \(\lambda\)F
= 80 x 10-2 x 480 = 384ms-1
Source: Myschool Past Questions Archive (Record #28264)
Physics
UTME / JAMB 1990
Waves, Sound & Vibrations
Solution
An organic pipe closed at one end is 80cm long. Determine the frequency of the fundamental note assuming that the speed of sound in air is 340ms-1
A
106Hz
B
213Hz
C
318Hz
D
425Hz
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
\(\lambda\) = 4L
= 4 x 80 = 320cm
Converting 320cm to m, we have 3.2m
F = \(\frac{V}{\lambda}\)
= \(\frac{340}{3.2}\)
= 106.25Hz
\(\approxeq\) 106Hz
Source: Myschool Past Questions Archive (Record #28265)
Physics
UTME / JAMB 1990
Waves, Sound & Vibrations
Solution
A sonometer wire of length 100cm under a tension of 10N, has a frequency of 250Hz. Keeping the length of the wire constant, the tension is adjusted to produce a new frequency of 350Hz. The new tension is
A
5.1N
B
7.1N
C
14.0N
D
19.6N
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
\(\frac{F_1}{F_2}\) = \(\sqrt\frac{T_1}{T_2}\)
\(\frac{250}{350}\) = \(\sqrt\frac{10}{T_2}\)
T2 = 19.6N
Source: Myschool Past Questions Archive (Record #28267)
Physics
UTME / JAMB 1990
Magnetism, Electromagnetism & AC Circuits
One of the properties of the earth's magnetic field is that the
A
north pole lies in the northern hemisphere
B
geographic and magnetic meridians coincide
C
earth's magnetic flux is entirely horizontal at a place where the magnetic dip is zero
D
earth's magnetic flux is entirely vertical at a place where the magnetic dip is zero
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 #28270)
Physics
UTME / JAMB 1990
Work, Energy, Power & Simple Machines
Solution
Which of the following statements are true of an insulated charged body carrying positive charge? i. it contains excess positive charges. ii. it creates an electric field. iii. it possesses potential energy. iv. it carries electric current.
A
i and iv only
B
i and ii only
C
i, ii, iii only
D
i, ii, iii and iv
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
The correct answer is C. i, ii, iii only, as the insulated charged body carries excess positive charges, creates an electric field, and possesses potential energy, but does not carry electric current(An insulated charged body carrying a positive charge does not carry electric current because it is not part of a circuit that allows the flow of charge.)
Source: Myschool Past Questions Archive (Record #28274)
Physics
UTME / JAMB 1990
Electrostatics & Capacitors
Which of the following is a vector?
A
Electric charge
B
Electric field
C
Electrical potential difference
D
Electrical capacitance
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 #28275)
Physics
UTME / JAMB 1990
Current Electricity & Electric Circuits
Solution
Three cells each of e.m.f. 1.5v and an internal resistance of 1.0\(\Omega\) are connected in parallel across a load resistance of 2.67\(\Omega\). Calculate the current in the load?
A
0.26A
B
0.41A
C
0.50A
D
0.79A
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
E = 1.5v
rT = \(\frac{1 \times 1\times 1}{(1\times1)+ (1\times1) +(1\times1)}\)
E.m. f = I(R + r) = 0.33\(\Omega\)
1.5 = I(2.67 + 0.33)
I = 0.5A
Source: Myschool Past Questions Archive (Record #28278)