Please answer all 4 of them Q1. Which of the following statements is wrong? a) Two stars are observed to have the same s
Posted: Wed Apr 27, 2022 7:38 am
Please answer all 4 of them
Q1.
Which of the following statements is wrong?
a) Two stars are observed to have the same spectral type but one
is much dimmer than the other. Given that both are main sequence
stars, then the dimmer star is at a farther distance from the Earth
than the brighter one.
b) If the solar system lies on the rotational axis of a binary
system, then the system cannot be a spectroscopic binary.
c) M stars are the most common type of main-sequence stars.
d) If we know the mass of a star, then its luminosity can be
determined.
Q2.
Star A has an apparent magnitude of -1. Sar B has an apparent
magnitude of 3.5. Star C has an apparent magnitude of 2. Assume
that now we are to redefine the apparent magnitude scale by setting
the apparent magnitude of star A to be 1 and the apparent magnitude
of star B to be 10. In the new logarithmic scale, what is the
apparent magnitude of star C?
a) 6.67
b) 7
c) 7.33
d) 6
Q3.
A Helium gas is initially at very low temperature. The
temperature is then increased steadily. The number densities of
Helium atoms, singly ionized Helium He+ and doubly
ionized Helium He2+ are measured. Which of the following
about the variations of number densities with time is correct?
a) He: Always decreases with time.
He+: First increases with time, reaching a maximum
and then decreases with time.
He2+: Always increases with time.
b) He: Always decreases with time.
He+: Always increases with time.
He2+: First increases with time, reaching a maximum
and then decreases with time.
c) He: Always decreases with time.
He+: Always increases with time.
He2+: Always increases with time.
d) He: Always decreases with time.
He+: First increases with time, reaching a maximum
and then decreases with time.
He2+: First increases with time, reaching a maximum
and then decreases with time.
Q4
The Sun has an absolute magnitude of 4.83. A star has an
absolute magnitude of 7.66 and a surface temperature of 30000 K.
Find the radius of the star.
a) 70000 km
b) 7000000 km
c) 700000 km
d) 7000 km
Q1.
Which of the following statements is wrong?
a) Two stars are observed to have the same spectral type but one
is much dimmer than the other. Given that both are main sequence
stars, then the dimmer star is at a farther distance from the Earth
than the brighter one.
b) If the solar system lies on the rotational axis of a binary
system, then the system cannot be a spectroscopic binary.
c) M stars are the most common type of main-sequence stars.
d) If we know the mass of a star, then its luminosity can be
determined.
Q2.
Star A has an apparent magnitude of -1. Sar B has an apparent
magnitude of 3.5. Star C has an apparent magnitude of 2. Assume
that now we are to redefine the apparent magnitude scale by setting
the apparent magnitude of star A to be 1 and the apparent magnitude
of star B to be 10. In the new logarithmic scale, what is the
apparent magnitude of star C?
a) 6.67
b) 7
c) 7.33
d) 6
Q3.
A Helium gas is initially at very low temperature. The
temperature is then increased steadily. The number densities of
Helium atoms, singly ionized Helium He+ and doubly
ionized Helium He2+ are measured. Which of the following
about the variations of number densities with time is correct?
a) He: Always decreases with time.
He+: First increases with time, reaching a maximum
and then decreases with time.
He2+: Always increases with time.
b) He: Always decreases with time.
He+: Always increases with time.
He2+: First increases with time, reaching a maximum
and then decreases with time.
c) He: Always decreases with time.
He+: Always increases with time.
He2+: Always increases with time.
d) He: Always decreases with time.
He+: First increases with time, reaching a maximum
and then decreases with time.
He2+: First increases with time, reaching a maximum
and then decreases with time.
Q4
The Sun has an absolute magnitude of 4.83. A star has an
absolute magnitude of 7.66 and a surface temperature of 30000 K.
Find the radius of the star.
a) 70000 km
b) 7000000 km
c) 700000 km
d) 7000 km