Physics 2015 JAMB Past Questions

Physics 2015 JAMB Past Questions

1.If the volume of a gas is recoded as 76cm³ at a temperature of 27°C with a pressure of 800mmHg. What will be the volume of the gas at S.T.P?

• A. 36.2cm³
• B. 25.7cm³
• C. 72.8cm³
• D. 24.3cm³

 

Explanation

General formular of Gas laws

(P₁V₁) ÷ T₁= (P₂V₂) ÷ T₂

P₁ = 800mmHg, V, = 76cm3, T_r = 273 + 27 = 300k

P₂ = 760mmHg, V₂ = ? T₂= 273 + 0 = 273 + 6 = 277k

(800 × 76) ÷ 300 = (760 × V₂) ÷ 273

V₂ = (300 × 76 × 273) ÷ (300 × 760) = 72.8 cm3

The volume of gas as S.T.P = 72.8 cm³

 

2. Boyle’s law may be Witten as

• A. P1V1= P2V2
• B. V1 = V2 ÷ T1T2
• C. P1T1 = P2T2
• D. P1V1 ÷ T1 = P1V1 ÷ T2

Correct Answer: Option A

Explanation

Boyle‘s law stats that the volume of a given mass of a gas, at a constant temperature is inversely proportional to us pressure.

Mathematically

V ∝ l/p, v = k/p (where k is constant)

K = VP

Let k = k1

Then, if k = k, V and P = V1P1

V1P1 = V2P2

 

 

3. The direction of the path taken by light is called

• A. Locus
• B. Lines
• C. Ray
• D. Beam

Correct Answer: Option C

Explanation

Ray – a beam of light or radiation

 

 

4. What is the inductance (L) of an inductor whose reactance is 1Ω at 50/ π hertz (H)?

• A. 100 H
• B. 0.01H
• C. 10H
• D. 1H 

Correct Answer: Option B

Explanation

XL = WL = 2πFL (w = 2πf)

XL = reactance inductor (S.I unit Ω)

L = inductance (L) in Henry

XL = 1Ω, f = 50/π, L = ?

1 = 2× π × 50/π × L

1 = 100L

i.e. 100L = 1

L = 1/100

0.01H

∴ Inductance (L) of a inductor = 0.01H

5. A stroboscope can be used to make the ware appear …………..

• A. Stationary
• B. In motion
• C. Dipper
• D. Ripple 

Correct Answer: Option A

Explanation

Stroboscope is a scientific instrument used to make a wave appears stationary when used

6

In an elastic collision

I. Energy is conserved
II. Energy is decreased
III. Energy is increased
IV. Linear momentum conversed

• A. I only
• B. I and IV only
• C. II only
• D. III only

Correct Answer: Option B

Explanation

In an inelastic collision, linear momentum is conserved and energy is decreased

Momentum and kinetic energy are conserved in elastic collision

 

7. Body floats in fluid when its …………………

• A. Displaces its own volume of the liquid (fluid)
• B. Displaces its own mass of the fluid
• C. Displace its own density of the fluid
• D. Is no longer subjected to gravity 

Correct Answer: Option B

Explanation

Note:The principle of floatation states that a floating body displaces its own weight of the fluid or which its float.

For object to sink weight of the object (W) > upthrust of the fluid (v) i.e. w > u

(i.e. weight of the body (or object) mass of the fluid)

 

8. The general gas law can be written as

• A. PV ÷ T = a constant
• B. PV = a constant
• C. v/t = a constant

• Correct Answer: Option A

  Explanation

  Formula for general gas law
  
  V × 1/T × P
  
  N [(PV) ÷ T] = K is constant D. p/T = a constant 

9. A motor boy of a driver saw what seem to appear to be a pool of water a head of him, while his driver’s drives a new truck on a funny day. Which of the following explains his observation?

• A. He saw a flying objects
• B. He must be thinking of water and food
• C. He was seeing the shadow of the car
• D. The sun ray from the sky were passing from a hot air (layer) to cold layer

Correct Answer: Option D

Explanation

The appearance of pool of water on road surfaces is called MIRAGE

His observation show that light from the sun ray refracted through a layer of hot air(layer) which is closed to the ground, passes from a hot air layer to the cold layer

 

 

10. Which of the following is not luminous object?

• A. The sun
• B. The moon
• C. light candle
• D. Star

Correct Answer: Option B

Explanation

Sun are self luminous source
Moon is a non – luminous

11. The resultant force of a couple is ………?

• A. Infinity
• B. Zero
• C. One
• D. Half

Correct Answer: Option B

Explanation

Note: moment of a couple = force × length (fL)

The tangential force is actingin an opposite direction alongside its length

i.e f1 L1 = f2L2

f2L2 − f1 L1 = 0(i.e Zero)

 

 

12. A vector quantity can only be completely described when ……… and …………are mentioned.

• A. Magnitude and motion
• B. Magnitude and direction
• C. Distance and specified displacement
• D. Moment and momentum

Correct Answer: Option B

Explanation

A vector quantity has both magnitude and direction

 

 

13. In which of the following device in the expansion of solid is a disadvantages?

I. Simple pendulum
II. Fire alarms
III. Thermostat
IV. Bimetallic thermometer

• A. III only
• B. II & III only
• C. I only
• D. II, III & IV only

Correct Answer: Option C

Explanation

Simple pendulum does not depend on thermal expansion

Five alarms, Thermostat and Bimetallic thermometer are application of thermal expansion of solid

 

 

14. If an object is placed at a height of tem above the ground at a stationary point. It posses what types of energy?

• A. Mechanical energy
• B. Stationary energy
• C. Potential energy
• D. Vibrational energy

Correct Answer: Option C

Explanation

Energy due to position T is potential energy (P.E)

Energy due to motion is kinetic energy (K.E)

 

 

15. Calculate the gravitation force of attraction between two planets of 10²⁴kg and 10²⁷kg separated by a distance of 10²⁰meters.

• A. 6.67N
• B. 6.56N
• C. 7.5N
• D. 8.6N 

Correct Answer: Option A

Explanation

F = (Gm₁m₂) ÷ r²

M₁ = 10₂₄Kg, M₂ = 10²⁷Kg , r = 10²

(Note: the gravitational constant of G = 6.67×107ndash;11 Nm2/Kg2

F = \( (6.67 × 10^{– 11 + 24 + 27)} 10^40 = 6.67 × (10^40 ÷ 10^40)

= 6.67N

f = 6.67N

 

16. Mr. F. Abioye observed his image though a plane mirror, kept a distance way from him at 4.7m in his room at what distance is the image found from Abioye eye?

• A. 9.4m
• B. 7.5m
• C. 5.7m
• D. 6.9m

Correct Answer: Option A

Explanation

As object and image are usually at equal distance apart from the mirror /p>

Distance between Abioye (a) and hip image (I) = AI

i.e. AI = 4.7 + 47

= 9.4m

 

 

17. Primary colours of light are

• A. Red, blue and green
• B. Cyan, magneta and yellow
• C. Black, blue and green
• D. None of these colour

Correct Answer: Option A

Explanation

Primary colours of light are red, blue and green

Secondary colours of light are cyan, magneta and yellow

 

18. Electrons were discovered by

• A. James Chadwick B.
• B. J.J Thompson
• C. Sir Isaac Newton
• D. Charles Newton

Correct Answer: Option B

Explanation

J.J. Thompson discovered ELECTRONS

 

 

19. What is the relationship mechanical advantage (MA) velocity Ratio (V.R) and efficiency with percentage?

• A. e = M.A/V.R × 100 %
• B. M.A = E.V.R
• C. V.R = 1 ÷ sin θ M.A
• D. M.A = 1/E × 100% 

Correct Answer: Option A

Explanation

he relationship between M.A, V.R, e and 100% can be written as

e = M.A/V.R × 100 %

i.e E/100 = M.A/V.R

= L ÷ E/x ÷ y = Ly/Ex

E/100 = Ly/Ex

 

 

20. The external parts of an object can be measure accurately through the use of which scientific instrument?

• A. Micrometer screw gauge
• B. Vernier Caliper
• C. Meter rule
• D. None of the instrument

Correct Answer: Option A

Explanation

Micrometer screw gauge measure an objects accurately (mainly on the external parts of the object). It measures the external parts of objects only

 

 

21. Convert 45°C to kelvin

• A. 318K
• B. 250K
• C. 184K
• D. 120K 

Correct Answer: Option A

Explanation

Note: T = 273 + θ

θ = 45°

T = 273 + 45

= 318K

 

 

22. A member of the crew of a SPACESHIP experiences weightlessness in a space when they

• A. Fall freely from the earth’s gravitational field
• B. Is walking on the planet
• C. In between the sun and the earth
• D. Holding anything in space is negative 

Correct Answer: Option A

Explanation

Weightlessness:– The state of being free from the effects of gravity. (zero gravity)

 

 

23. Radio waves belong to the class of wave whose velocity is about

• A. 34m/s
• B. 3 ×10⁶m/s
• C. 3 ×10⁸m/s
• D. 3 × 10^-8m/s

 

Correct Answer: Option C

Explanation

A radio waves is an electromagnetic waves which travels with a constant velocity of 3 × 10⁸m/s

 

 

24. At 35°C and 5 atmospheres pressure the density of a gas is 0. 600g per liter. What is the density at 7 atmospheric pressure and 350°C.

• A. 0.27g / liters
• B. 0.25g / liters
• C. 1.7g / liters
• D. 0.15g / liters 

Correct Answer: Option C

Explanation

θ1=35°CT1=273+θ=73+35=308kP1=5atm

d1 = 0.600g/ litre

θ2 = 350°C, T2 = 2 + 3 + θ

= 273 + 350 = 623k, d2 = ?

P2 = 7atm

T a P a 1/d = TPK/d (where k is a constant)

Tp1 ÷ d1 = T1P2 ÷ d2, [(308 × 5) ÷ 0.600]

= (623 × 7) ÷ d2

d2 = (623 × 7 ×0.600) ÷ (308 × 5)

= 2616.6 ÷ 1540

= 1.69g / litresd2 = 1.69g / litres

∴ d2 = 1.70g / litres (Approx.)

 

 

25. The compressed regions and the space-out regions in longitude wave are refers to as

• A. Compression and Rarefaction
• B. Comparison and Explosion
• C. Reflection only
• D. Refraction only

Correct Answer: Option A

Explanation

The vibrating particles behave like a spiral spring with a series of compression region and space–out region.