JAMB UTME - Physics - 2020
Tambaya 1 Rahoto
Bayanin Amsa
A Mercury-in-glass thermometer works by measuring the expansion of mercury in a glass tube as the temperature increases. The lower fixed point is typically the point where the mercury is at its minimum and the upper fixed point is where the mercury is at its maximum. In this case, the lower fixed point is at 0°C and the upper fixed point is at 30°C, and the mercury is 210mm above the lower fixed point. So, the temperature of the room must be 30.43°C.
Tambaya 2 Rahoto
Bayanin Amsa
Tambaya 3 Rahoto
Bayanin Amsa
| Heat energy = Electrical Energy |
| Hence, |
| MCθ = power x time |
| 5 x 1 x 10−2 x C = 100 x 20 |
| C = 200 |
| 5×102 |
| = 4 x 104 J/kg/oC |
Tambaya 4 Rahoto
Which of the following conditions are necessary and sufficient for total internal reflection to take place at the boundary between two optical media?
I. Light is passing from optical denser medium to optically less dense medium
II. Light is passing from optically less dense medium to optically denser medium to optically denser medium
III. Angle of incidence is greater
IV. Angle of incidence is lesser
Bayanin Amsa
Tambaya 5 Rahoto
Bayanin Amsa
| Let N = count rate at zero time |
| N 3min→ N 3min→ N |
| 2 4 |
| N |
| 4 |
| 400 |
| N = 400 x N |
| N/4 |
| N = 1600 |
Tambaya 6 Rahoto
The fiqure above represents a block-and-tackle pulley system on which an effort of W Newtons supports a load of 120.0N. If the efficiency of the machine is 40 , then the value of W is
Bayanin Amsa
| V.E = 6, load = 120N |
| Efficiency = M.A x 1 x 100% |
| V.R |
| 40 = 120 x 1 x 100 |
| effort 6 1 |
| Effort = 50N |
Tambaya 7 Rahoto
In an experiment in which molten naphtha-line is allowed to cool, the cooling curve i n the figure was obtained. The temperature 80 0c is known as the
Tambaya 8 Rahoto
Bayanin Amsa
Tambaya 9 Rahoto
Tambaya 10 Rahoto
Bayanin Amsa
Tambaya 11 Rahoto
Bayanin Amsa
The other options, 5.165cm and 5.0cm, may not be as accurate as they do not match up with the smallest increment that can be measured using vernier callipers.
Tambaya 12 Rahoto
Bayanin Amsa
Radioactivity is the spontaneous emission of radiation from atomic nuclei. This radiation can consist of alpha, beta, and gamma radiation.
Natural radioactivity is a purely nuclear phenomenon. The nucleus of a radioactive substance is unstable and such an unstable nucleus undergoes spontaneous breakdown (disintegration). The process continues until a stable nucleus is obtained.
Tambaya 13 Rahoto
Bayanin Amsa
Tambaya 14 Rahoto
Which of the following pairs is NOT part of the electromagnetic spectrum?
I. Radio waves
II. Beta rays
III. Gamma rays
IV. Alpha rays
Bayanin Amsa
Tambaya 15 Rahoto
In the figure, the value of R is
Bayanin Amsa
| RT = V =12 = 6? |
| 1 2 |
| RT = 3 + R×6 |
| R+6 |
| R = 6Ω |
Tambaya 16 Rahoto
In what range of temperature is the expansion of water anomalous?
Bayanin Amsa
Tambaya 17 Rahoto
Which of the following statements about radioactivity is true?
(i) Alpha particle is positively charged
(ii) Beta particle is negatively charged
(iii) Gamma ray is neutral
(iv) Beta particle has the same mass as helium atom
(v) Gamma ray is charged.
Bayanin Amsa
Tambaya 18 Rahoto
Two mirrors of the same length are arranges as show in the diagram. A ray of light NO strikes the system at O and emerges along PQ. The emergent ray has been deviated through
Bayanin Amsa
| Angle of deviation = ?1+?2 = 50 + 50 + 40 + 40 |
| = 180o |
Tambaya 19 Rahoto
Bayanin Amsa
Tambaya 20 Rahoto
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)
Bayanin Amsa
| A) RT = 2 + 3 + 6 = 11Ω |
| (B) RT = 3×3 = 1.2Ω |
| 2+3 |
| (C) RT = 3×2×6 |
| (2×3)+(2×6)+(3×6) |
| = 1Ω |
| (D) RT = 3 + 2×6 |
| 2+6 |
| = 4.5 Ω |
Tambaya 21 Rahoto
Bayanin Amsa
Tambaya 22 Rahoto
The effect of closing the key K in the circuit shown in the figure above would be to?
Bayanin Amsa
| When K is open, the total Resistance = 8 + 2 = 10? |
| 1 = V? = 6v? = 0.6A |
| When K is closed, 18+18=1? |
| 28=1? |
| ? = 82 = 4? |
| ? = 82 = 4? |
| 4? in series with 2?= 6? |
| 1 = V? = 66 = 1A |
| 1 - 0.6A = 0.4A |
| Hence, 0.4A increase |
Tambaya 23 Rahoto
Consider the three forces acting at O and in equilibrium as shown in the figure. Which of the following equations is/are CORRECT?
I. \(P_1 \sin \theta_1 = p_1 \cos \theta_2\)
II. \(P_3 = P_1 \cos \theta_4 + P_2 \cos_2\)
III. \(P_1 \sin \theta_1 = p_2 \sin \theta_2\)
Bayanin Amsa
From ?ABC
P = P1 cos ? From ACD
|
Tambaya 24 Rahoto
Tambaya 25 Rahoto
Which of the following instruments consumes the highest current?
| I. Electric iron | 250v | 1kW |
| II. Television set | 220v | 110W |
| III. Torch light | 6v | 30W |
| IV.Immersion heater | 110v | 500W |
Tambaya 26 Rahoto
Bayanin Amsa
Difference in time = 1 sec
Echo time = 1 / 2 = 0.5 sec
Difference of cliff from ship = 0.5 x 250
= 125m
Tambaya 27 Rahoto
Bayanin Amsa
| MaVa = MbVb |
| 5 x Va = 0.05 x 100 |
| Va = 1m−1 |
Tambaya 29 Rahoto
Bayanin Amsa
Tambaya 30 Rahoto
Which of the following statements about defects of vision is/are CORRECT?
I. For a long sighted person, close objects appear blurred
II. For a short sighted person, distant objects appear blurred
III. Short sight is corrected by using a pair of converging lenses
Tambaya 31 Rahoto
Bayanin Amsa
Tambaya 33 Rahoto
A hydrometer is an instrument for measuring the
Bayanin Amsa
Tambaya 34 Rahoto
Bayanin Amsa
Tambaya 35 Rahoto
Tambaya 36 Rahoto
Bayanin Amsa
Tambaya 37 Rahoto
Bayanin Amsa
| 3 x α = V2−V1 |
| V1×Δθ |
| 3 x 2 x 10−5 = V2−10 |
| 100×10 |
| V2 = (100 x 10 x 3 x 2 10−2) + 10 |
| = 10.6 cm3 |
Tambaya 38 Rahoto
A few grains of table salt were put in a cup of cold water, kept at constant temperature and left undistributed. Eventually all the water tested salty. This action is due to?
