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JAMB UTME - Physics - 1997

Question 1 Rapport

Light of velocity 3 x 108ms-1 is incident on a material of reflective of index n. If the velocity of light is reduced to 2.4 x 108ms-1 in the material, what is n?

2.33

2.25

1.33

1.25

Détails de la réponse

The question is asking about the index of refraction of a material that is being hit by light. The speed of light changes when it passes through a material, which is described by the index of refraction. The question gives the velocity of light in a vacuum and in the material, so we can use the equation n = c/v, where c is the speed of light in a vacuum and v is the speed of light in the material, to find the index of refraction. Plugging in the given values, we get n = 3 x 10^8 m/s / (2.4 x 10^8 m/s) = 1.25. Therefore, the correct answer is.

Voir la réponse

Question 8 Rapport

An object of mass 100g projected vertically upwards from the ground level has a velocity of 20ms-1 at a height of 10m. calculate its initial kinetic energy at the ground level.[g = 10ms-2, neglect air resistance]

10 J

20 J

30 J

50 J

Détails de la réponse

Using, v2 = u2 - 2gx

(20)2 = u21/2 x 10 x 10

u2 = 600(m/s)2

initial K.E = - mu2

= $\frac{1}{2}$ x 600

= 30 J

Lisez la note de cours sur Scalars And Vectors (WAEC)

Scalars And Vectors

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Question 14 Rapport

A body of mass 2kg moving vertically upwards has its velocity increased uniformly from 10ms-1 to 40ms-1 in 4s. Neglecting air resistance, calculate the upward vertical force acting on the body.[g = 10 ms-1]

15N

20N

35N

45N

Détails de la réponse

F = mg + ma

F = 2 [10 + $\frac{(40 - 10)}{4}$ ]

F = 35 N

Lisez la note de cours sur Scalars And Vectors (WAEC)

Scalars And Vectors

Voir la réponse

Question 19 Rapport

The voltage of the domestic electric supply is represented by the equation \(V = 311 \sin 314.2t\). Determine the frequency of the a.c. supply \([\pi = 3.142]\)

50.0Hz

100.0Hz

311.0Hz

314.2Hz

Détails de la réponse

V = 311 sin314.2t compare with,

V = V sin2 $π$ Ft

2 $μ$ F = 314.2

F = $\frac{314.2}{2 \times 3.142}$

F = 50Hz

Voir la réponse

Question 21 Rapport

Two bodies X and Y are projected on the same horizontal plane, with the same initial speed but at angles 30 and 60 respectively to the horizontal. Neglecting air resistance, the ratio of the range of X to that of Y is

1:1

1:2

√3:1

√3

Détails de la réponse

Range =

\frac{U^{2} s i n 2 θ}{g}

$\frac{R_{x}}{R_{y}}$ = $\frac{U_{x}^{2} s i n 60}{U_{y}^{2} s i n 120}$

sin60o = sin120o

$\frac{R_{x}}{R_{y}}$ = $\frac{1}{1}$

hence, = 1:1

Lisez la note de cours sur Motion (JAMB)

Voir la réponse

Question 22 Rapport

Three electric cells each of e.m.f 1.5V and internal resistance of 1.0 \(\Omega\) are connected in parallel across an external resistance of \(\frac{2}{3}\Omega\). Calculate the value of the current in the resistor

0.5 A

0.9A

1.5A

4.5A

Détails de la réponse

E.m.f = 1.5

r = $\frac{1 \times 1 \times 1}{(1 \times 1) + (1 \times 1) + (1 \times 1)}$

r = $\frac{1}{3}$ $Ω$

I = $\frac{E . m . f}{r + R}$

I = $\frac{1.5}{\frac{1}{3} + \frac{2}{3}}$

I = 1.5A

Lisez la note de cours sur Current Electricity (JAMB)

Current Electricity

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Question 30 Rapport

In the diagram above, which of the angles \( \theta_1 \), \( \theta_2 \), \( \theta_3 \) and \( \theta_4 \) is the angle of deviation of the ray of light passing through the glass prism XYZ?

θ3

θ2

θ_{1}

θ4

Voir la réponse

Question 31 Rapport

Under constant tension and constant mass per unit length, the note produced by a plucked string is 500Hz when the length of the string is 0.90m. At what length is the frequency 150Hz?

3m

4m

5m

6m

Détails de la réponse

F =

\frac{1}{2 L}

\sqrt{\frac{T}{m}}

F1L1 = F2L2

500 x 0.9 = 150 x L2

therefore, L2 = 3m

Lisez la note de cours sur Motion (JAMB)

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Question 32 Rapport

The distance xm travelled by a particle in time t seconds is described by the equation x = 10 + 12t2, Find the average speed of the particle between the time interval t = 2s and t = 5s

60 ms-1

72 ms-1

84 ms-1

108 ms-1

Détails de la réponse

speed =

\frac{d x}{d t}

$\frac{d x}{d t}$ = 10 + 12t2

$\frac{d x}{d t}$ = 24t

$\frac{d x}{d t}$ =24 x 3

$\frac{d x}{d t}$ = 72 ms-1

Lisez la note de cours sur Motion (WAEC)

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Question 36 Rapport

The length of mercury thread when it is at 0^oC, 100^oC and at an unknown temperature \( \theta \) is 25mm, 225mm and 175mm respectively. The value of \( \theta \) is

85.0oC

80.0oC

75.0oC

70.0oC

Détails de la réponse

\frac{θ - 0}{100 - 0}

=

\frac{175 - 25}{225 - 25}

$θ$ = 75.0oC

Lisez la note de cours sur Measurements And Units (JAMB)

Measurements And Units

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Question 37 Rapport

In a meter bridge experiment, two resistor \(2\Omega\) and \(3\Omega\) occupy the left and right gaps respectively. Find the balance point from the left side of the bridge

20cm

40cm

60cm

80cm

Détails de la réponse

Let the point be x

$\frac{2}{x}$ = $\frac{3}{100 - x}$

making x subject of formula,

2(100 - x) = 3x

200 - 2x = 3x

200 = 3x + 2x

200 = 5x

divide both side by 5

x = 40cm

Lisez la note de cours sur Equilibrium Of Forces (WAEC)

Equilibrium Of Forces

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Question 38 Rapport

An electric water pump rate 1.5 kW, lifts 200kg of water through a vertical height of 6 meters in seconds. What is the efficiency of the pump? [g = 10ms-2, neglecting air resistance]

90.0%

85.0%

80.0%

65.0%

Détails de la réponse

Efficiency = output x 100

= $\frac{\frac{200 \times 10 \times θ}{10}}{1500}$ x $\frac{100}{1}$

= 80%

Lisez la note de cours sur Electrical Energy And Power (JAMB)

Electrical Energy And Power

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Question 42 Rapport

A planet has mass m1 and is at a distance r, from the sun. A second planet has mass m2 = 10m1 and at a distance of r2 = 2r1 from the sun. Determine the ratio of the gravitational force experienced by the planets.

1 : 5

2 : 5

3 : 5

4 : 5

Détails de la réponse

g =

\frac{G M}{R^{2}}

$\frac{G_{1} M_{1}}{r_{1}^{2}}$ = $\frac{G_{2} M_{2}}{r_{2}^{2}}$

$\frac{G_{1} M_{1}}{r_{1}^{2}}$ = $\frac{G_{2} \times 10 M_{1}}{(2 r_{1})^{2}}$

$\frac{G_{1}}{G_{2}}$ = $\frac{2}{5}$

Lisez la note de cours sur Gravitational Field (JAMB)

Gravitational Field

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