JAMB UTME - Physics - 2020
Ajụjụ 1 Ripọtì
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.
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Ajụjụ 2 Ripọtì
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Ajụjụ 3 Ripọtì
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Ajụjụ 4 Ripọtì
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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.
Ajụjụ 5 Ripọtì
Ajụjụ 6 Ripọtì
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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.
Ajụjụ 7 Ripọtì
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Ajụjụ 8 Ripọtì
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| MaVa = MbVb |
| 5 x Va = 0.05 x 100 |
| Va = 1m−1 |
Ajụjụ 9 Ripọtì
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Ajụjụ 10 Ripọtì
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
Ajụjụ 11 Ripọtì
Which of the following pairs is NOT part of the electromagnetic spectrum?
I. Radio waves
II. Beta rays
III. Gamma rays
IV. Alpha rays
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Ajụjụ 12 Ripọtì
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Ajụjụ 13 Ripọtì
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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.
Ajụjụ 14 Ripọtì
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| 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 |
Ajụjụ 15 Ripọtì
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Difference in time = 1 sec
Echo time = 1 / 2 = 0.5 sec
Difference of cliff from ship = 0.5 x 250
= 125m
Ajụjụ 16 Ripọtì
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?
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Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration until they are evenly distributed. It occurs in various substances, such as gases, liquids, and solids, and is driven by the random motion of molecules. This process plays a crucial role in many biological and physical phenomena, such as the movement of oxygen and carbon dioxide across cell membranes, the dispersion of perfume in the air, and the mixing of solutes in solutions.
Ajụjụ 17 Ripọtì
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
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| Angle of deviation = ?1+?2 = 50 + 50 + 40 + 40 |
| = 180o |
Ajụjụ 18 Ripọtì
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Ajụjụ 19 Ripọtì
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Ajụjụ 20 Ripọtì
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)
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| 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 |
Ajụjụ 21 Ripọtì
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 |
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Ajụjụ 22 Ripọtì
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| 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 |
Ajụjụ 23 Ripọtì
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Ajụjụ 24 Ripọtì
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
Ajụjụ 25 Ripọtì
In the figure, the value of R is
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| RT = V =12 = 6? |
| 1 2 |
| RT = 3 + R×6 |
| R+6 |
| R = 6Ω |
Ajụjụ 27 Ripọtì
Ajụjụ 28 Ripọtì
In what range of temperature is the expansion of water anomalous?
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Ajụjụ 29 Ripọtì
A hydrometer is an instrument for measuring the
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Ajụjụ 30 Ripọtì
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
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Ajụjụ 31 Ripọtì
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Ajụjụ 32 Ripọtì
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. \(P_1 \sin \theta_1 = p_2 \sin \theta_2\)
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From ?ABC
P = P1 cos ? From ACD
|
Ajụjụ 33 Ripọtì
Ajụjụ 34 Ripọtì
The effect of closing the key K in the circuit shown in the figure above would be to?
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| 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 |
Ajụjụ 35 Ripọtì
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Ajụjụ 36 Ripọtì
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| 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 |
Ajụjụ 37 Ripọtì
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Ajụjụ 38 Ripọtì
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
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| 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 |
