At what temperature will the rms speed of oxygen molecules become just sufficient for escaping from the Earths atmosphere? (Given : Mass of oxygen molecule (m) = 2.76 × 10^{-26}kg Boltzmanns constant $k_{B} = 1.38 × 10^{-23} JK^{-1})$
|
Answer
|
The efficiency of an ideal heat engine working between the freezing point and boiling point of water, is
|
Answer
|
A carbon resistor of (47 ± 4.7) kΩ is to be marked with rings of different colours for its identification. The colour code sequence will be
|
Answer
|
A set of n equal resistors, of value R each, are connected in series to a battery of emf E and internal resistance R. The current drawn is I. Now, the n resistors are connected in parallel to the same battery. Then the current drawn from battery becomes 10 I. The value of n is
|
Answer
|
A battery consists of a variable number n of identical cells (having internal resistance r each) which are connected in series. The terminals of the battery are short-circuited and the current I is measured. Which of the graphs shows the correct relationship between I and n?
|
Answer
|
Unpolarised light is incident from air on a plane surface of a material of refractive index $\mu$. At a particular angle of incidence i, it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation?
|
Answer
|
In Youngs double slit experiment the separation d between the slits is 2 mm, the wavelength $\lambda$ of the light used is 5896 Å and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20°. To increase the fringe angular width to 0.21° (with same $\lambda$ and D) the separation between the slits needs to be changed to
|
Answer
|
An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of
|
Answer
|
The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom, is
|
Answer
|
An electron of mass m with an initial velocity $\overrightarrow{V}= V_{o}\hat{i}\left(V_{o}>0\right)$ enters an electric field $\overrightarrow{E}= -E_{o}\hat{i}\left(E_{o}= constant >0 \right)$ at t=0 . If $\lambda_{o}$ is its de-Broglie wavelength initially, then its de-Broglie wavelength at time t is
|
Answer
|