2015 - JAMB Physics Past Questions and Answers - page 6
51
The dimension of universal gravitational constant is……….?
A
\( M^{–1}L^3 T^{–2} \)
B
ML3T2
C
ML3
D
MLT-2
correct option: a
f α (MM ÷g2)
F(GMM ÷ r2) [G – gravitational constant]
GMM = Fr2
G = F02 ÷ MM = m × aπr2 ÷ MM (f = ma)
= (m × m5-2 × r2) ÷ MM
= (Kg.m52 × m2) ÷ Kg.Kg
=1 ÷ kg.m3.52
The dimension mathematically representation have a quantities of M, L AND T
M (Mass) = kg, L (Length) = M, T (Time) second
G = kg-1 m2.52(Using dimension rule)
M-1.L3.T-2
∴ The universal gravitational constant (G) =\( M^{–1}L^3 T^{–2} \)
Users' Answers & CommentsF(GMM ÷ r2) [G – gravitational constant]
GMM = Fr2
G = F02 ÷ MM = m × aπr2 ÷ MM (f = ma)
= (m × m5-2 × r2) ÷ MM
= (Kg.m52 × m2) ÷ Kg.Kg
=1 ÷ kg.m3.52
The dimension mathematically representation have a quantities of M, L AND T
M (Mass) = kg, L (Length) = M, T (Time) second
G = kg-1 m2.52(Using dimension rule)
M-1.L3.T-2
∴ The universal gravitational constant (G) =\( M^{–1}L^3 T^{–2} \)
52
A good electric cell should have the following except
A
A minimum of polarization effect
B
A long life
C
A cheap and safe electrolytes
D
Cost and dangerous of the cell
correct option: d
A good electric cell should proses the following
1. A long life of an electric cell,
2. A minimum of polarization effect
3. A cheap and safe electrolytes
Except D cost and dangerous of the electric cell
Users' Answers & Comments1. A long life of an electric cell,
2. A minimum of polarization effect
3. A cheap and safe electrolytes
Except D cost and dangerous of the electric cell
53
The r.m.s value of a supply voltage is quoted at 200v. What is the approximate peak value of the voltage?
A
200volts
B
300volts
C
283volts
D
250volts
correct option: c
Vr.m.s = V0 ÷ V2, where Vr.m.s rep. to as voltage root –square mean, v = peak voltage
Vr.m.s = 200volt, v = ?
200 = V0 ÷ V2
V0 = 200v2
= 200 × 1.414
= 282.8 volts V0 = b &approx.; 283 volts
Users' Answers & CommentsVr.m.s = 200volt, v = ?
200 = V0 ÷ V2
V0 = 200v2
= 200 × 1.414
= 282.8 volts V0 = b &approx.; 283 volts
54
Heat transfer by convection will take place is one the following substance.
A
Stone
B
Wood
C
Mercury
D
Water
correct option: d
Convection take place commonly in liquids (water) and slightly in gasses
Users' Answers & Comments55
A regular spacing or arrangement of atoms in a crystalline material is called
A
Orbit
B
Lattice
C
Atomic structure
D
Energy level
correct option: b
The regular arrangement of atoms in a crystalline materials is called LATTICES
Users' Answers & Comments56
The net movement of solvent molecules from a region of high solvent potential to a region of lower solvent potential through a partially or semi permeable membrane is refer to as
A
Diffusion
B
Osmosis
C
Surface tension
D
Cohesion
correct option: b
Diffusion: The movement of water vapors from regions of low concentration toward regions of high concentration
Surface tension: is a force transmitted through a sting or object surface tension = force (N) ÷ Area m2(Nm−2)
Users' Answers & CommentsSurface tension: is a force transmitted through a sting or object surface tension = force (N) ÷ Area m2(Nm−2)
57
Which of the following option is right if an object fall freely to the ground?
1. The total energy is Kinetic
2. The ratio of potential energy to kinetic energy is constant
3. The sum of potential and kinetic is constant
1. The total energy is Kinetic
2. The ratio of potential energy to kinetic energy is constant
3. The sum of potential and kinetic is constant
A
1 only
B
2 only
C
3 only
D
1 and 2 only
correct option: c
The total energy at any point combination of the PE and KE
i.e. TEnergy = PE + K.E
= mgh + ½ mr2
= ½ m (gh + v2 )
= ½ m (v2 + gh)
∴ TEnergy = ½ m (V2 + gh)
∴ Total energy at the height (hm) = PE + KE
The sum of P.E and KE at any point is always constant .
Users' Answers & Commentsi.e. TEnergy = PE + K.E
= mgh + ½ mr2
= ½ m (gh + v2 )
= ½ m (v2 + gh)
∴ TEnergy = ½ m (V2 + gh)
∴ Total energy at the height (hm) = PE + KE
The sum of P.E and KE at any point is always constant .
58
The eyeball consists of a round tough white skin called
A
Sclerotic
B
Choroid coal
C
Optical fiber
D
Accommodation
correct option: a
Sclerotic coat (sclera) is the tough outer coat of the eye that coves the eyeball (ii) sclerotic coat is modified in front of the eye to from a transparent and horny window
Users' Answers & Comments59
Which one of the following is a vector quantity?
A
Temperature gradient
B
Mass
C
Work
D
Time
correct option: a
Temperature gradient(Tg) = DT ÷ L = T2 – T1 ÷ L
i.e– it is the ratio of an increment in temperature to the length
Hence, Temperature gradient (Tg) has defined direction alongside with magnitude
And it is a vector gratuity
Mass, work & Time are scalar quantity
Users' Answers & Commentsi.e– it is the ratio of an increment in temperature to the length
Hence, Temperature gradient (Tg) has defined direction alongside with magnitude
And it is a vector gratuity
Mass, work & Time are scalar quantity
60
Efficiency of a transformer is equal to
A
Efficiency of transformer = (secondary coil ÷ primary coil) × 100%
B
Efficiency of transformer = (mechanical advantage ÷ velocity ratio) × 100%
C
Efficiency of a transformer = (Number of turns in the secondary coil ÷ Number of turns in the primary coil) × 100%
D
Efficiency of a transformer = (power developed in the secondary coil ÷ power supplied to the primary coil) × 100%
correct option: d
Efficiency of a transformer = (power developed in the secondary coil ÷ power supplied to the primary coil) × 100%
Users' Answers & Comments