1. Tardigrade
  2. Question
  3. Physics
  4. Many exoplanets have been discovered by the transit method, where in one monitors, a dip in the intensity of the parent star as the exoplanet moves in front of it. The exoplanet has a radius R and the parent star has radius 100 R. If I0 is the intensity observed on earth due to the parent star, then as the exoplanet transits

Q. Many exoplanets have been discovered by the transit method, where in one monitors, a dip in the intensity of the parent star as the exoplanet moves in front of it. The exoplanet has a radius $R$ and the parent star has radius $100\, R$. If $I_{0}$ is the intensity observed on earth due to the parent star, then as the exoplanet transits

KVPYKVPY 2018Thermal Properties of Matter Report Error

Solution:

Intensity of radiation (mainly visible light) emitted from surface of a star is proportional to its area
So, $I \propto A$ or $I= KA$
where, k = constant
Now, if $I_{0}$ = intensity of parent star
Then, $I_{0}=K\pi (100\,R)^{2}=k\,\pi\,R^{2}\times 10000$
When exoplanet is in front of star, observed intensity will be minimum. Let intensity minimum is $I_\min$, then
$I_{\min}=K[\pi (100\,R)^{2}-\pi\,R^{2}]$
image
$\Rightarrow I_\min =k \pi R^{2}(10000-1)$
$=k \pi R^{2} \times 9999$
So, $\frac{I_{\min}}{I_{0}}$
$=\frac{k\pi\,R^{2}\times 9999}{k\pi\,R^{2}\times 10000}$
$\Rightarrow I_\min=I_{0}\times 0.9999$

Questions from KVPY 2018

1. Air (density $\rho$) is being blown on a soap film (surface tension $T$) by a pipe of radius $R$ with its opening right next to the film. The film is deformed and a bubble detaches from the film when the shape of the deformed surface is a hemisphere. Given that the dynamic pressure on the film due to the air blown at speed $\upsilon$ is $\frac{1}{2}\rho\upsilon^{2},$ the speed at which thle bubbe formed is

Mechanical Properties of Fluids

2. For an ideal gas, the internal energy is given by $U = 5 _{p} V /2 + C,$ where $C$ is a constant. The equation of the adiabats in the $pV-$plane will be

Thermodynamics

3. An ideal gas undergoes change in its state from the initial state $I$ to the final state $F$ via two possible paths as shown below. Then,

4. A thermally insulated rigid container of $1 L$ volume contains a diatomic ideal gas a t room temperature. A small paddle installed inside the container is rotated from the outside, such that the pressure rises by $10^5\, Pa$. The change in internal energy is close to

5. In Young’s double slit experiment, the amplitudes of the two waves incident on the two slits are $A$ and $2A.$ If $I_0$ is the maximum intensity, then the intensity at a spot on the screen, where the phase difference between the two interfering waves is $\phi.$

Questions from Thermal Properties of Matter

1. If the temperature difference on the two sides of a wall increases from $ 100{}^\circ C $ to $ 200{}^\circ C $ , its thermal conductivity

Rajasthan PMT 2007

2. A wall is made of equally thick layers $A$ and $B$ of different materials. Thermal conductivity of $A$ is twice that of $B$. In the steady state, the temperature difference across the wall is $36^{\circ}C$. The temperature difference across the layer $A$ is

3. The radiation emitted by a star $A$ is $10,000$ times that of the sun. If the surface temperatures of the sun and the star $A$ are $8000 \, K$ and $2000 \, K$ respectively. The ratio of the radii of the star $A$ and the sun is

NTA Abhyas 2020

4. A black body at $1373$ $℃$ emits maximum energy corresponding to a wavelength of $1.78$ microns. The temperature of the moon for which $\lambda _{m}=14$ micron would be

NTA Abhyas 2020

5. Three rods made from the same material and having the same cross-sectional area, form the sides of an isosceles triangle $ABC$ , right-angled at $B$ . The points $A$ and $B$ are maintained at temperature $T$ and $\sqrt{2}T$ , respectively. In steady-state, the temperature of the point $C$ is $T_{C}$ . Assuming that only heat conduction takes place along the lengths of the rods, the value of $\frac{T_{C}}{T}$ is

NTA Abhyas 2020

Physics Most Viewed Questions

1. If $E$ and $G$ respectively denote energy and gravitational constant, then $\frac{ E }{ G }$ has the dimensions of:

NEET 2021 Physical World, Units and Measurements

2. The de Broglie wavelength of an electron moving with kinetic energy of $144 \,eV$ is nearly

NEET 2020 Dual Nature of Radiation and Matter

3. A car starts from rest and accelerates at $5\, m / s ^{2}$ At $t=4\, s$, a ball is dropped out of a window by a person sitting in the car. What is the velocity and acceleration of the ball at $t =6\, s$ ? (Take $\left. g =10\, m / s ^{2}\right)$

NEET 2021 Motion in a Straight Line

4. A wheel with $20$ metallic spokes each $1\, m$ long is rotated with a speed of $120\, rpm$ in a plane perpendicular to a magnetic field of $0.4\, G$. The induced emf between the axle and rim of the wheel will be, $(1 G = 10^{-4}\, T)$

NEET 2020 Electromagnetic Induction

5. A barometer is constructed using a liquid (density $= 760 \,kg/m^{3})$ What would be the height of the liquid column, when a mercury barometer reads $76\, cm$ ?
(density of mercury $= 13600 kg/m^{3})$

NEET 2020 Mechanical Properties of Fluids

Latest Updates