Assertion : A pulsor is a source of radio waves which change in terms of intensity at regular interval of time
Reason : A pulsor is a rotating neutron star
A
If both assertion and reason are true and the reason is the correct explanation of the assertion.
✓
If both assertion and reason are true but reason is not the correct explanation of the assertion.
C
If assertion is true but reason is false.
D
If the assertion and reason both are false.
Answer
Correct option: B.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
Suppose a planet goes around Sun with a linear speed twice as fast that of earth. What will be it's orbit size as compared to that of earth ? (Radius of earth = R)
A planet of mass $m$ moves in an ellipse around the sun of mass $M_s$ so that its maximum and minimum distances are $r_1$ and $r_2$ respectively. The angular momentum of the planet relative to the centre of the sun is
A
$\sqrt{\frac{2 G M_{S r_1}}{\left(r_1+r_2\right)}}$
✓
$\sqrt{\frac{2 G M_s m^2 r_1 r_2}{\left(r_1+r_2\right)}}$
C
$\sqrt{\frac{ GM _{ s } r _1 r_2}{\left(r_1+r_2\right)}}$
D
$\sqrt{\frac{2 G M_s}{r_1 r_2\left(r_1+r_2\right)}}$
Answer
Correct option: B.
$\sqrt{\frac{2 G M_s m^2 r_1 r_2}{\left(r_1+r_2\right)}}$
$\sqrt{\frac{2 G M_1 m^2 r_1 r_2}{\left(r_1+r_2\right)}}$
Consider a binary star system consisting of two stars of masses $\mathrm{M}_1$ and $\mathrm{M}_2$ separated by a distance of 30 AU with a period of revolution equal to 30 years. If one of the two stars is 5 times farther from the centre of mass than the other. The masses of the two stars in terms of solar masses are
A galaxy is observed to be moving with a velocity of $8600 km-sec^{–1}.$ If it is at a distance of 430 million light year from us, Hubble constant and corresponding age of the universe are respectively
A bright star is indicated to have a brightness magnitude of – 5 compared to a star of brightness zero magnitude. It means that this star compared to the reference star of zero brightness is
The sun revolves around the galaxy with a speed of $250 \mathrm{~km} / \mathrm{sec}$ and it's radius is $3 \times 10^4$ light year. The mass of the milky way is
There are certain types of stars called visible stars which undergo periodic change in their light output. If such a star quadruple it's light output, how much does it's magnitude change
A particular emission line, detected in the light from a galaxy, has a wavelength $\lambda^{\prime}=1.1 \lambda$, where $\lambda$ is the proper wavelength of the line. The galaxy distance from us
A double star is a system of two stars rotating about their centre of mass only under their mutual gravitational attraction. Let the star have mass m and 2m and their separation be l. Their time period of rotation about their centre of mass will be proportional to
The sun emits a light with maximum wavelength 510 mm while another star X emits a light with maximum wavelength of 350 nm. What is the ratio of surface temperature of sun and the star X
A planet of mass M has a satellite of mass m, revolving around the planet in a circular orbit of radius r and time period T. The mass (M) of the planet is
✓
$\frac{4 \pi^2 r^3}{G T^2}$
B
$\frac{4 \pi^2 r ^2}{ GT ^3}$
C
$\frac{ GT ^2}{4 \pi r ^8}$
D
$\frac{ r ^8 G }{4 \pi T ^2}$
Answer
Correct option: A.
$\frac{4 \pi^2 r^3}{G T^2}$
(a) $\frac{4 \pi^2 r^3}{G T^2}$
Correct option is A. $\frac{4 \pi^3 r^3}{G T^2}$
$F=\frac{G M m}{r^2}=m r \omega^2=m r\left(\frac{2 \pi}{T}\right)^2$
$M=\frac{m r^3 4 \pi^2}{G m T^2}=\frac{4 \pi^3 r^3}{G T^2}$
The wavelength of maximum energy, released during an atomic explosion, was $2.93 \times 10^{-10} \mathrm{~m}$. Given that the Wien's constant is $2.93 \times 10^{-3} \mathrm{~m} \mathrm{~K}$, the maximum temperature attained must be of the order of
The solar constant on the surface of the earth is S. What will be its value on the surface of another planet which is about 5.3 A.U. away from sun
A
$\frac{S}{5.3}$
✓
$\frac{S}{(5.3)^2}$
C
$5.3 S$
D
$(5.3)^2 S$
Answer
Correct option: B.
$\frac{S}{(5.3)^2}$
(b) $\frac{S}{(5.3)^2}$
Solar constant is the energy crossing per unit area per sec at earth's distance, area being normal to the sun's rays. Also energy galling is inversely proportional to the square of distance from the source.
Hubble showed that the universe as a whole is expanding and the distant stars are receding from us. The spectral line from a star, when compared with the corresponding line from an source will then show
✓
A shift in frequency towards the red end
B
A shift in frequency towards the violet end
C
No shift in frequency at all
D
A shift in frequency towards the violet end as well as a decrease in intensity