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Physics
UTME / JAMB 1982
Electricity and Magnetism
A magnetic needle is suspended first at the earth's north magnetic pole and then at a point on the magnetic equator. The respective angles between the needle and the horizontal are
A
0o and 0o
B
60o and 60o
C
90o and 90o
D
90o and 0o
E
0o and 90o
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 #28931)
Physics
UTME / JAMB 1982
Electricity and Magnetism
Diagram
Solution
what is the resultant resistance in the circuit given above
Attached Figure / Diagram
A
11Ω
B
8Ω
C
4Ω
D
3.6Ω
E
4.3Ω
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
The 2\(\Omega\) resistors are in parallel
R\(_{para}\) = \(\frac{R_1 \times R_2}{R_1 + R_2}\) = \(\frac{2 \times 2}{2 + 2}\) = \(\frac{4}{4}\) = 1 \(\Omega\)
This 1 \(\Omega\) resistor is in series with both the 4 \(\Omega\) and 3 \(\Omega\) resistors
Therefore, R\(_{total}\) = 1 + 4 + 3 = 8 \(\Omega\)
Source: Myschool Past Questions Archive (Record #41624)
Physics
UTME / JAMB 1981
Electricity and Magnetism
Which of the following elements are real magnetic materials?
A
Iron, steel and nickel
B
copper, steel and iron
C
lead, iron and brass
D
glass, lead and steel
E
stone, air and iron
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 #28977)
Physics
UTME / JAMB 1981
Electricity and Magnetism
Which of the following is NOT an effect that can be produced by an electric current?
A
heat
B
light
C
sound
D
motion
E
none of the above
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #28984)
Physics
UTME / JAMB 1981
Electricity and Magnetism
Solution
A cell of e.m.f 2V and internal resistance 1\(\Omega\) supplies a current of 0.5 amps to a resistance whose value is
A
0.5\(\Omega\)
B
1\(\Omega\)
C
2\(\Omega\)
D
2.5\(\Omega\)
E
3\(\Omega\)
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
1 = \(\frac{E}{R + r}\)
\(\frac{2}{R + 1}\) = 0.5
0.5R = 2 - 0.5 = 1.5
R = \(\frac{1.5}{0.5}\)
= 3\(\Omega\)
Source: Myschool Past Questions Archive (Record #28992)
Physics
UTME / JAMB 1981
Electricity and Magnetism
The resistance of an open series circuit is
A
zero
B
half the normal resistance of the circuit
C
double the normal resistance of the circuit
D
one
E
infinite
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #29016)
Physics
UTME / JAMB 1981
Electricity and Magnetism
Solution
Alternating current can induce voltage because it has a
A
ripple value
B
varying magnetic field
C
weaker magnetic field than direct current
D
stonger magnetic field than direct current
E
high peak value
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Due to the change in the voltage in an AC, which either increases or decreases, the magnetic field around it is alwats eithercollapsing or expanding (varying magnetic field).
Source: Myschool Past Questions Archive (Record #29019)
Physics
UTME / JAMB 1981
Electricity and Magnetism
Which of the following is NOT directly associated with direct current (DC)?
A
A dry cell
B
a moving coil galvanometer
C
a transformer
D
a lead- acid accumulator
E
a commutator
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #29032)
Physics
UTME / JAMB 1981
Electricity and Magnetism
Solution
A transformer has 300 turns of wire in the primary coil and 30 turns in the secondary coil.If the input voltage is 100 volts, the output voltage is
A
5 volts
B
10 volts
C
15 volts
D
20 volts
E
25 volts
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
for transformer,
Es = Ns, Es = e.m.f of secondary
Ep = Np, Ep = e.m.f of primary
NS = number of turns in secondary
Ns = number of turns in primary
\(\frac{30}{300}\) = \(\frac{x}{100}\)
300X = 3000X
= 10 volts
Source: Myschool Past Questions Archive (Record #29041)
Physics
UTME / JAMB 1981
Electricity and Magnetism
A closed coil of wire is placed near a magnet. The magnet lies along the axis of the coil. Under which of the following conditions would there be no current in the coil?
A
When the coil is moved toward the stationary magnet
B
When the coil is moved away from the stationary magnet
C
when the coil is held stationary but the magnet is moved towards the coil
D
when both the coil and the magnet are held stationary
E
when the coil is held stationary but the magnet is moved away from the cell
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 #29042)
Physics
UTME / JAMB 1981
Electricity and Magnetism
Diagram
Solution
The effect of closing the key K in the circuit shown above would be to
Attached Figure / Diagram
A
increase the current by 0.6A
B
reduce the current by 0.6A
C
increase the current by 0.4A
D
keep the current unchanged
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
When K is open, the total resistance
R = 8\(\Omega\) + 2\(\Omega\) = 10\(\Omega\)
I = \(\frac{V}{R}\) = \(\frac{6}{10}\)
= 0.6A
When K is closed, we have
\(\frac{1}{R}\) = \(\frac{1}{8}\) + \(\frac{1}{8}\)
⇒ \(\frac{1}{R}\) = \(\frac{1}{4}\)
⇒ R = 4\(\Omega\)
The total resistance R = 4\(\Omega\) + 2\(\Omega\)
= 6\(\Omega\)
I = \(\frac{6}{6}\)
= 1A
Hence, I = 1A - 0.6A = 0.4A increase
Source: Myschool Past Questions Archive (Record #41616)
Physics
UTME / JAMB 1980
Electricity and Magnetism
Which of the following is true of an electrical charge?
A
positive charge means deficit electrons
B
negative charge means excess of electrons
C
electric current means movement of electrons
D
all of the above
E
A and B only
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 #29055)
Physics
UTME / JAMB 1980
Electricity and Magnetism
Solution
What is the relative permitivity of a capacitor if its capacitance with a medium as dielectric is 16 farads and its capacitance with vacuum as dielectric is 2 farads?
A
o
B
\(\frac{1}{2}\)
C
2
D
8
E
32
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
E = Er x E0
16 = Er x 2
Er = 8
Source: Myschool Past Questions Archive (Record #29091)
Physics
UTME / JAMB 1980
Electricity and Magnetism
Solution
A milliameter of resistance 5\(\Omega\) and full scale deflection of 50m A is to used to measure a potential difference of 50 V. The resistance of the multiplier should be
A
95\(\Omega\)
B
110\(\Omega\)
C
595\(\Omega\)
D
995\(\Omega\)
E
1005\(\Omega\)
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
V = IR
50 = 50 x 10\(^{-3}\) (5 + R)
R = 995\(\Omega\)
Source: Myschool Past Questions Archive (Record #29104)
Physics
UTME / JAMB 1980
Electricity and Magnetism
The best material for the core of the primary and secondary coils of an induction coil is
A
copper, because it has a good conductor of electricity
B
steel, because it becomes magnetic and retains its magnetism for a long time
C
rubber, because it is a good insulator and the user is prevented from shock
D
soft iron, because it becomes magnetic but easily loses its magnetism
E
glass, because it is transparent
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 #29120)