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Physics
UTME / JAMB 2011
Current Electricity & Electric Circuits
Solution
If the charge of electricity is K wh is N4, what is the cost of operating an electrical appliance rated 250 v,2 A for six hours?
A
N28
B
N12
C
N16
D
N24
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Energy consumed = power x time = lvt = 2 x 250 x 6hr = 300 wh = 3 kwh but 1 kwh = N4
3 kwh = 3 x N4 = N 12
Source: Myschool Past Questions Archive (Record #14463)
Physics
UTME / JAMB 2011
Current Electricity & Electric Circuits
Solution
Under which of the following conditions do gases conduct electricity?
A
Low presssure and low p.d
B
low pressure and high p.d
C
high pressure an low p.d
D
high pressure and high p.d
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Under high potential difference and low pressure gases are good conductor of electricity
Source: Myschool Past Questions Archive (Record #14464)
Physics
UTME / JAMB 2011
Current Electricity & Electric Circuits
Solution
Three similar cells each of e.m.f 2 v and internal resistance 2Ω are connected in parallel, the total e.m.f and total internal resistance are respectively
A
6 v, 6.0Ω
B
2 v, 0.7Ω
C
2 v, 6.0Ω
D
6 v, 0.7Ω
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Total energy in parred connection is equal to emt of one cell, = 2v but total internal resistance is given by
(1)/r = (1)/r1 + (1)/r2 + (1)/r3 = (1)/2 + (1)/2 + (1)/2 = (3)/2
∴ r = (2)/3 = 0.67Ω
Source: Myschool Past Questions Archive (Record #14443)
Physics
UTME / JAMB 2011
Lenses & Optical Instruments
Solution
When the human eye loses its power of accomodation, the defect is known as
A
short sightedness
B
presbyopia
C
astigmatism
D
long sightedness
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
presbyopia is loss of accommodation
Source: Myschool Past Questions Archive (Record #14453)
Physics
UTME / JAMB 2011
Current Electricity & Electric Circuits
Solution
When a red rose flower is observed in blue light, what colour does the observer see?
A
Red
B
Blue
C
Magenta
D
yellow
E
No correct option
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
The colour which an object presents to the eye is the colour of light it reflects. Red rose flower will therefore absorb any other colour and reflect red. Therefore when viewed in blue light, it has no colur to reflect and will therefore appear black. Although mixture of red light and blue light = magenta .
Source: Myschool Past Questions Archive (Record #14455)
Physics
UTME / JAMB 2011
Electrostatics & Capacitors
Solution
The capacitance of a parallel plate capacitor is 20 μf in air and 60 μf in the presence of a dielectric. What is the dielectric constant?
A
0.3
B
6.0
C
3.0
D
2.0
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Dielectric constant = (c)/c° = (60)/20 = 3
Source: Myschool Past Questions Archive (Record #14458)
Physics
UTME / JAMB 2011
Lenses & Optical Instruments
Solution
A certain far - sighted person cannot see object that are closer to the eye than 50 cm clearly. Determine the power of the converging lens which will enable him to see at 25 cm
A
0.06 D
B
0.02 D
C
0.03 D
D
0.04 D
E
no option is correct
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
\(\frac{1}{\text{f}}\) = \(\frac{1}{\text{u}}\) + \(\frac{1}{\text{v}}\)
\(\frac{1}{\text{f}}\) = \(\frac{1}{25}\) + \(\frac{1}{-50}\)
u = 25cm, v = - 50cm
\(\frac{1}{\text{f}}\) = \(\frac{1}{u}\) - \(\frac{1}{50}\) = \(\frac{2 - 1}{50}\)
f = 50cm
P = \(\frac{1}{\text{f}}\) = \(\frac{1}{50}\) = 0.02cm. ( in dioptres = 2D)
1D = 1m\(^{-1}\)
Source: Myschool Past Questions Archive (Record #14459)
Physics
UTME / JAMB 2011
Magnetism, Electromagnetism & AC Circuits
Solution
Two inductors of inductance 4 II and 8 II are arrange in series and a current of 10 A is passed through them. What is the energy stored in them?
A
600 J
B
50 J
C
133 J
D
250 J
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Inductance (L) in series: 4 + 8 = 12
Therefore Energy stored =
W = \(\frac{1}{2} LI^2\)
= \(\frac{1}{2} \times 12 \times 10^2\)
= 600J
Source: Myschool Past Questions Archive (Record #14465)
Physics
UTME / JAMB 2011
Current Electricity & Electric Circuits
Solution
Which of the following materials has an increase in resistance with temperature?
A
water
B
metals
C
wood
D
electrolyte
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Resistance in metals are proportional to temperature
Source: Myschool Past Questions Archive (Record #14466)
Physics
UTME / JAMB 2011
Current Electricity & Electric Circuits
The bond between silicon and germanium is
A
covalent
B
ionic
C
dative
D
electrovalent
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #14467)
Physics
UTME / JAMB 2011
Atomic, Quantum, Nuclear Physics & Electronics
Solution
A radioactive isotope has a decay constant of 10-5s4. Calculate half life
A
6.93 x 10-5s
B
6.93 x 105s
C
6.93 x104s
D
6.93 x 10-4s
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
T (1)/2 = (0.693)/\lambda = (0.693)/10-5
= 0.693 x 105
= 6.93 x 104 sec
Source: Myschool Past Questions Archive (Record #14469)
Physics
UTME / JAMB 2011
Current Electricity & Electric Circuits
The electrical properties of germanium can be altered drastically by the addition of impurity. This process is referred to as
A
saturation
B
bonding
C
amplification
D
dopping
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #14470)
Physics
UTME / JAMB 2011
Atomic, Quantum, Nuclear Physics & Electronics
Solution
If the threshold frequency for tungsten is 1.3 x 1015Hz, what is its work function?
[H = 6.6 x 10-34 Js]
A
8.58 x 10-19 J
B
8.50 x 10-15 J
C
8.58 x 10-17 J
D
8.85 x 10-18
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Work function, w = hfo 6.6 x 10-34 x 1.3 x 1015
= 8.58 x 10-19
Source: Myschool Past Questions Archive (Record #14471)
Physics
UTME / JAMB 2011
Current Electricity & Electric Circuits
Solution
Which of the following will be applied when a metal Y is used to electroplate another metal X in electrolysis?
A
X is the anode and very high current is used
B
X is the anode and Y is the cathode
C
Y is the cathode and X is the anode
D
Y is the anode and very high current is used
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
Metals and hydrogen are deposited at the cathode, while non-metals and oxygen are deposited on the anode
∴ metals Y will form the anode which is deposited at the cathode made of x
Source: Myschool Past Questions Archive (Record #14472)
Physics
UTME / JAMB 2011
Current Electricity & Electric Circuits
Solution
Two resistors 5Ω and 10Ω are arranged first in series and later in parallel to a 24V source, the ratio of total power dissipated in the series and parallel arrangements respectively is
A
5:3
B
1:50
C
50:1
D
3:5
E
No Correct Option
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
Power in Series Arrangement
Total Resistance (R_series): R\(_{series}\) = R\(_1\) + R\(_2\) = 5Ω + 10Ω = 15Ω
Total Power (P_series): P = \(\frac{V^2}{\text{R}}\) = \(\frac{24^2}{15}\) = 38.4W
Power in parallel Arrangement
Total Resistance(R\(_{parallel}\)): R\(_{parallel}\) = \(\frac{R_1 \times R_2}{R_1 + R_2}\) = \(\frac{5 \times 10}{5 + 10}\) = 3.33
Total Power(P_{parallel}\): P = \(\frac{V^2}{\text{R}}\) = \(\frac{24^2}{3.33}\) = 172.8W
Ratio of Powers
Power ratio = \(\frac{\text{Pseries}}{\text{Pparallel}}\) = \(\frac{38.4}{172.8}\) = \(\frac{1}{4.5}\) = \(\frac{2}{9}\)
Therefore, there is no correct answer.
Source: Official Exam / Past Question Archive