2020 - JAMB Physics Past Questions and Answers - page 2
Natural radioactivity consists of emission___
\(\alpha\)-particles and \(\beta\)-rays
\(\alpha\)-particles and X-rays
\(\gamma\)-ray and X-rays
\(\alpha\)-particles and \(\beta\)-rays and \(\gamma\)-rays
Radioactivity is the spontaneous emission of radiation from atomic nuclei. This radiation can consist of alpha, beta, and gamma radiation.
Natural radioactivity is a purely nuclear phenomenon. The nucleus of a radioactive substance is unstable and such an unstable nucleus undergoes spontaneous breakdown (disintegration). The process continues until a stable nucleus is obtained.
If a source of solid is moving, a stationary listener will hear a sound of different frequency. This is called?
doppler effect
resonance
ultra sound
rarefaction
The Doppler effect is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who described the phenomenon in 1842. Wikipedia
Which of the following can be described as high tension transmission?
High resistance and low voltage
Low current and high voltage
High current and low voltage
High current and low resistance
What is the cost of running five 50W lamps and four 100W lamps for 10 hours if electrical energy costs 2 Kobo per KWh?
N0.65
N0.39
N3.90
N0.13
P = (5 x 50) + (100 x 4)
= 650watts
Energy(kWhr) = 650 x 10-3 x 10
= 6.5 kWhr
1kWhr cost 2 kobo ; 6.5 kWhr will cost 2×6.512×6.51
= 13 kobo
The mass of a proton is approximately equal to that of
an \(\alpha\)-particle
a \(\beta\)-Particle
a neutron
an electron
The mass of a proton is equal to that of the hydrogen atom. A hydrogen atom consists of one electron and one proton.
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 input voltage is
5 volts
10 volts
15 volts
20 volts
Es = e.m.f. of the secondary coil
Ep = Np
Np = e.m.f. of secondary coil
Ns = number of turns in secondary coil
Ns = number of turns in primary coil
\(\frac{30}{300}\) = \(\frac{x}{100}\) = 300
X = 3000
X = 10 volts
A solid weighs 4.8g in air, 2.8g in water and 3.2g in Kerosine. The ratio of desity of the solid to that of the kerosine is
2
\(\frac{3}{2}\)
\(\frac{2}{3}\)
3
Relative density of solid is given as
\(\frac{\text{weight of solid}}{\text{weight of an equal volume of water}}\)
= \(\frac{4.8}{4.8 - 2.8}\)
= \(\frac{4.8}{2}\) = 2.4
Relative density of liquid
= \(\frac{\text{Weight of liquid kerosine}}{\text{Weight of an equal volume of water}}\)
= \(\frac{4.8 - 3.2}{4.8 - 2.8}\) = \(\frac{1.6}{2}\) = 0.8
= \(\frac{\text{Ratio of relative density of solid}}{\text{Relative density of Kerosine}}\)
= \(\frac{\text{density of solid}}{\text{density of Kerosine}}\)
= \(\frac{2.4}{0.8}\)
= 3
One of the following readings represents the measurement of the measurement of the length of a metal rod using vernier callipers. Taking the reading accuracy into consideration, the most likely one is
5.165cm
A. 5.165cm
5.0cm
5.160cm
When a sound wave passes from air into water its
speed and frequency increases but its wavelength remains the same
speed and wavelength increases but its frequency remains the same
speed decreases
speed increases but its frequency and wavelength decreases
A convex mirror is used as a driving mirror because
I. its image is erect
II. It has a large field of view
III. It has a long focal length
Identify the CORRECT statement(s)
I and III only
I and II only
II and IIII only
I, II and III only
(A) R\(_T\) = 2 + 3 + 6 = 11\(\Omega\)
(B) R\(_T\) = \(\frac{3 \times 3}{2 + 3}\) = 1.2\(\Omega\)
(C) R\(_T\) = \(\frac{3 \times 2 \times 6}{(2 \times 3) + (2 \times 6) + (3 \times 6)}\)
= 1\(\Omega\)
(D) R\(_T\) = 3 + \(\frac{2 \times 6}{2 + 6}\)
= 4.5 \(\Omega\)