1993 - JAMB Physics Past Questions and Answers - page 4
31
Which of the following devices may be used to step up the voltage in a d.c. circuit?
A
a step-up transformer
B
a d.c. generator
C
a wattmeter
D
an induction coil
correct option: b
Users' Answers & Comments32
The primary aim in high tension transmission is to
A
minimize electrical energy losses due to heat production
B
increase the rate of energy transfer by using high voltage
C
increase the current in the wire
D
generate electricity at high current and low voltage
correct option: a
Users' Answers & Comments33
Determine the inductive reactance when a 30.0mH inductor with a negligible resistance is connected to a 1.3 x 103Hz oscillator.
A
39.0\(\Omega\)
B
122.5\(\Omega\)
C
245.0\(\Omega\)
D
39000.0\(\Omega\)
correct option: c
XL = 2\(\pi\)FL
= 2 x 3.142 x 30 x 10-3 x 1.3 x 103
= 245\(\Omega\)
Users' Answers & Comments= 2 x 3.142 x 30 x 10-3 x 1.3 x 103
= 245\(\Omega\)
34
Which of the following statements correctly describe(s) cathode rays? i. they consist of tiny particles carrying negative electric charges. ii. they are deflected in a magnetic field but not in an electric field. iii. they consist of fast moving neutrons and deflected in an electric field.
A
i only
B
ii only
C
i and ii only
D
ii and iii only
correct option: a
Users' Answers & Comments35
Natural radioactivity is the random spontaneous disintegration of the nuclei of heavy isotopes of certain elements with the emission of
A
\(\alpha\), X, and \( \beta\)
B
\(\alpha\), \(\beta\) and \(\gamma\)-rays
C
X, \(\alpha\), \(\gamma\)-ray
D
\(\alpha\), \( \beta\) and X-rays
correct option: b
Users' Answers & Comments36
Which of the following are produced after a nuclear fusion process? i. one heavy nucleus. ii. neutrons-1. iii. protons. iv. Energy.
A
i and ii
B
i and iv
C
ii and iii
D
ii and iv
correct option: b
Users' Answers & Comments37
An element X of an atomic number 88 and mass number 226 decays to form an element Z by emitting two beta particles and an alpha particle. Z is represented by
A
\(^{222}_{82}Z\)
B
\(^{222}_{88}Z\)
C
\(^{226}_{86}Z\)
D
\(^{226}_{80}Z\)
correct option: b
\(^{226}_{88}X\) \(\to\) \((^{0}_{-1}e)\) + \(^{4}_{2}\alpha\) + \(^{b}_{a}X\)
a + 2 + (-2) = 88 a \(\Rightarrow\) a = 88
b + 4 + 0 = 266 b \(\Rightarrow\) b = 222
Users' Answers & Commentsa + 2 + (-2) = 88 a \(\Rightarrow\) a = 88
b + 4 + 0 = 266 b \(\Rightarrow\) b = 222
38
The kinetic theory of photoelectron liberated from a metallic surface depends on the
A
intensity of the incident radiation
B
time duration of the incident radiation
C
temperature of the incident radiation
D
frequency of the incident radiation
correct option: d
Users' Answers & Comments39
A
75m
B
150m
C
300m
D
375m
correct option: a
Users' Answers & Comments40
A
9N
B
18N
C
20N
D
200N
correct option: d
Users' Answers & Comments