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Physics
UTME / JAMB 2022
Current Electricity
Solution
A cell whose internal resistance is 0.55\(\Omega\) delivers a current of 4 A to an external resistor. The lost voltage of the cell is?
A
4.00 V
B
2.20 V
C
0.15 V
D
8.00 V
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Lost voltage = I x R
= 4 x 0.55
= 2.2V
Source: WAEC / JAMB / NECO Classroom Archive (Record #64923)
Physics
UTME / JAMB 2022
Current Electricity
Solution
Which of the following liquid is a poor conductor of electricity?
A
Distilled water
B
Tap water
C
Sea water
D
Drinking water
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Distilled water is free of salts and is a poor conductor of electricity.
Source: WAEC / JAMB / NECO Classroom Archive (Record #64924)
Physics
WAEC / WASSCE 2022
Energy and Power
Solution
A galvanometer with a full-scale deflection of 20 mA is Converted to read 8 K by connecting a 395 \(\Omega\) resistor in series with it. Determine the internal resistance of the galvanometer
A
2.5\(\Omega\)
B
5.0\(\Omega\)
C
8.0\(\Omega\)
D
10.0\(\Omega\)
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
r = resistance of the galvanometer
l = current through galvanometer = 20mA or 0.02A
V1 = p.d across the galvanometer = I X r = 0.02 X r
: V1 = 0.02r
V2 = p.d across the multiplier = 8 - 0.02r
R = resistance of the multiplier = 395\Omega
where R = \(\frac{V}{I}\)
--> 395 = \(\frac{8−0.02r}{0.02}\)
CROSS MULTIPLY
8−0.02r = 395 * 0.02
8−0.02r = 7.9
--> 0.02r = 8 - 7.9
∴ r = \(\frac{0.1}{0.02}\)
= 5\Omega
Source: WAEC / JAMB / NECO Classroom Archive (Record #63335)
Physics
WAEC / WASSCE 2022
Energy and Power
Solution
A lamp is rated 240 V, 60 W. Determine the resistance of the lamp when lit?
A
120\(\Omega\)
B
240\(\Omega\)
C
540\(\Omega\)
D
960\(\Omega\)
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
P = 60w, V = 240v, R = ?
P = \(\frac{V^2}{R}\)
: 60 = \(\frac{240^2}{R}\)
→ R * 60 = 57,600
R = \(\frac{57,600}{60}\)
R = 960\(\Omega\)
Source: WAEC / JAMB / NECO Classroom Archive (Record #63347)
Physics
UTME / JAMB 2022
Energy and Power
Solution
A current of 0.5 A flows through a resistor when connected to a 40 V battery. How much energy is dispatched in 2 minutes?
A
2400 J
B
9600 J
C
1500 J
D
1200 J
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Energy = power x time
Power = voltage x current.
Energy = voltage x current x time
Energy = 40 x 0.5 x 60 x 2
→ 2,400j
Source: WAEC / JAMB / NECO Classroom Archive (Record #64937)
Physics
WAEC / WASSCE 2022
Simple Ac Circuit
Solution
In a series R-L-C circuit at resonance, impedance is----
A
maximum
B
minimum
C
capacitive
D
inductive
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
This is because, at resonance, the reactive components (inductive and capacitive reactance) cancel each other out, resulting in only the resistive component contributing to the impedance.
Source: WAEC / JAMB / NECO Classroom Archive (Record #63346)
Physics
WAEC / WASSCE 2022
Structure of the Atom
Solution
If the kinetic energy of an electron is 100 eV, what is the wavelength of the de-Broglie wave associated with it? [h = 6.6 x 10\(^{-34}\) J s, e = 1.6 x 10\(^{-19}\)C, m\(_{e}\), = 9.1 x 10\(^{-31}\) kg]
A
1.22 x 10\(^{-10}\)m
B
4.10 x 10\(^{-10}\)m
C
3.90 x 10\(^{-10}\)m
D
5.50 x 10\(^{-14}\)m
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
de broglie wavelength formula in terms of kinetic energy:
\lambda = \(\frac{h}{\sqrt{2mE}}\)
\lambda = \(\frac{6.6 \times 10^{-34}}{\sqrt{2 \times 9.1 \times10^{-31} \times100\times 1.6 \times 10^{-19}}}\)
\lambda = 1.22 x 10\(^{-10}\)m
NOTE; E = 100eV = 100 x 1.6 x 10\(^{-19}\)J
Source: WAEC / JAMB / NECO Classroom Archive (Record #63368)
Physics
WAEC / WASSCE 2022
Semi Conductor
Solution
In doping an intrinsic semiconductor to produce a p-type semiconductor,
A
the semiconductor is heated up
B
a donor element is added
C
an acceptor element is added
D
the semiconductor is conducted to a battery
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
If the dominant impurity atoms are ACCEPTOR type in the semiconductor, it will have a majority of holes over the electrons [p-type].
Source: WAEC / JAMB / NECO Classroom Archive (Record #63354)
Physics
UTME / JAMB 2022
Semi Conductor
Solution
A semiconductor is formed by?
A
co-ordinate bonds
B
electrovalent bonds
C
a substance free of bonds
D
covalent bonds
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
It's generally created using silicon, germanium, or other pure elements.
Semiconductors are created by adding impurities to the element.
The conductance or inductance of the element depends on the type and intensity of the added impurities.
The electrons surrounding each atom in a semiconductor are part of a covalent bond
Source: WAEC / JAMB / NECO Classroom Archive (Record #65090)
Physics
WAEC / WASSCE 2022
Structure of the Nucleus
Solution
The speed of fast-moving neutrons in a nuclear reactor can be reduced by using?
A
graphite rods
B
concrete shield
C
iron rods
D
boron rods
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Moderation is the process of the reduction of the initial high speed (high kinetic energy) of the free neutron.
Since energy is conserved, this reduction of the neutron speed takes place by transfer of energy to a material called a moderator.
There are several different types of moderating materials, and each have places where they are used more effectively.
Typically-used moderator materials include heavy water, light water, and graphite.
Source: WAEC / JAMB / NECO Classroom Archive (Record #63342)
Physics
WAEC / WASSCE 2022
Structure of the Nucleus
Solution
Arrange the following radiations in order of increasing ionization of air.
I. Alpha
Il. Gamma
IIl. Beta
A
I < III < II
B
II < I < III
C
II < III < I
D
I < II
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Alpha particles are highly ionising because of their double positive charge, large mass (compared to a beta particle) and because they are relatively slow.
They can cause multiple ionisations within a very small distance.
And the gamma radiation has the least ionising power.
Source: WAEC / JAMB / NECO Classroom Archive (Record #63361)
Physics
WAEC / WASSCE 2022
Structure of the Nucleus
Solution
Gamma rays are produced when?
A
high velocity electrons are abruptly stopped in metals
B
energy changes occur within the nuclei of atoms
C
energy changes occur within the electronic structure of atoms
D
electrons are deflected in very strong magnetic fields
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Gamma rays are produced in the disintegration of radioactive atomic nuclei and in the decay of certain subatomic particles.
Gamma radiation is emitted by excited nuclei or other processes involving subatomic particles;
it often accompanies alpha or beta radiation, as a nucleus emitting those particles may be left in an excited (higher-energy) state.
Source: WAEC / JAMB / NECO Classroom Archive (Record #63375)
Physics
UTME / JAMB 2022
Structure of the Nucleus
Solution
An isotope has an initial activity of 120 Bq. 6 days later its activity is 15 Bq. The half-life is?
A
3 days
B
2 days
C
1 day
D
4 days
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
The equation that establishes a relationship between the amount left undecayed,
A, the initial amount, A0, and the number of half-lives that pass in a period of time t looks like this:
\(\frac{1}{2^n} * A_0 = A\)
\(\frac{1}{2^n} * 120 = 15\)
\(\frac{1}{2^n}\) = \(\frac{15}{120}\)
\(\frac{1}{2^n}\) = \(\frac{1}{8}\)
\(\frac{1}{2^n}\) = \(\frac{1}{2^3}\)
\(2^n = 2^3\)
n = 3
:6days \div 3 = 2days
Source: WAEC / JAMB / NECO Classroom Archive (Record #64925)
Physics
WAEC / WASSCE 2022
Wave Particle Paradox
Solution
A body of mass, M, moving with velocity, V, has a wavelength, X, associated with it. This phenomenon is called----------
A
photoelectric effect
B
heisenberg's uncertainty principle
C
compton effect
D
wave-particles paradox
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
De Broglie equation, \lambda = h/mv, is used to describe the wave properties of matter, which suggests that matter can behave as a wave or particles, thereby leading to the wave-particle paradox.
Source: WAEC / JAMB / NECO Classroom Archive (Record #63320)
Physics
WAEC / WASSCE 2022
Reflection of Light
Solution
Which of the following descriptions of the image formed by a plane mirror is not correct. the image is----
A
erect and of the same size as the object
B
laterally inverted and of the same size as the object
C
erect and bigger than the object
D
virtual and if the same size
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Images formed by plane mirrors are virtual, upright, left-right reversed, the same distance from the mirror as the object's distance, and the same size as the object.
Source: WAEC / JAMB / NECO Classroom Archive (Record #63091)