Recent questions tagged 2018

In Young's double slit experiment the separation d between the slit is 2mm, the wavelength $\lambda$ of the light used is $5896 \; A^o$ and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is $0.20^o$. To increase the fringe angular width to $0.21^o$ ( with same $\lambda$ and D ) the separation between the slits needs to be changed to

asked Aug 21, 2018 by pady_1

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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?

asked Aug 21, 2018 by pady_1

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In the combination of the following gates the output Y can be written in terms of inputs A and B as

asked Aug 21, 2018 by pady_1

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In a p-n junction diode, change in temperature due to heating

asked Aug 21, 2018 by pady_1

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In the circuit shown in the figure, the input voltage $V_i$ is 20 V, $V_{BE}$ = 0 and $V_{CE}$ = 0. The value of $I_B, \; I_C$ and $\beta$ are given by

asked Aug 21, 2018 by pady_1

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The refractive index of the material of a prism is $\sqrt{2}$ and the angle of the prism is $30^o$. One of the two refracting surfaces of the prism is made a mirror inwards, by silver coating. A beam of monochromatic light entering the prism from the other face will retrace its path (after reflecting from the silvered surface) if its angle of incidence on the prism is

asked Aug 21, 2018 by pady_1

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The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance

asked Aug 21, 2018 by pady_1

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An em wave id propagating in a medium with a velocity $\overrightarrow{V} = V \hat{i}$. The instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along

asked Aug 21, 2018 by pady_1

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An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm. If the object is displaced through a distance of 20 cm towards the mirror, the displacement of the image will be :

asked Aug 21, 2018 by pady_1

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An inductor 20 mH, a capacitor $100 \; \mu F$ and a resistor $50 \Omega$ are connected in series across a source of emf, $V = 10 \sin 314 \;t$. The power loss in the circuit is

asked Aug 21, 2018 by pady_1

1 answer

A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains gravitational potential energy. The work required to do this comes from

asked Aug 21, 2018 by pady_1

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A metallic rod of mass per unit length $0.5 \; kg \; m^{-1}$ is lying horizontally on a smooth inclined plane which makes an angle of $30^o$ with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction 0.25 T is acting on it in the vertical direction. The current flowing in the rod to keep it stationary is

asked Aug 21, 2018 by pady_1

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Current sensitivity of a moving coil galvanometer is 5 div/mA and its voltage sensitivity (angular deflection per unit voltage applied ) is 20 div/V. The resistance of the galvanometer is

asked Aug 21, 2018 by pady_1

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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 :

asked Aug 21, 2018 by pady_1

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A carbon resistor of $(47 \pm 4.7) \; k \Omega$ is to be marked with rings of different colours for its identification. The colour code sequence will be :

asked Aug 21, 2018 by pady_1

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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 ?

asked Aug 21, 2018 by pady_1

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The volume (V) of a monatomic gas varies with its temperature (T), as shown in the graph. The ratio of work done by the gas, to the heat absorbed by it, when it undergoes a change from state A to state B, is

asked Aug 21, 2018 by pady_1

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The fundamental frequency in an open organ pipe is equal to the third harmonic of a closed organ pipe. If the length of the closed organ pipe is 20 cm, the length of the open organ pipe is :

asked Aug 21, 2018 by pady_1

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At what temperature will the rms speed of oxygen molecules become just sufficient for escapig from the Earth's atmosphere ? (Given : Mass of oxygen molecule (m) = $2.76 \times 10^{-25} kg$ Boltzmann's constant $(K_B) = 1.38 \times 10^{-23} JK^{-1}$ )

asked Aug 21, 2018 by pady_1

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The effciency of an ideal heat engine workong between the freezing point and boiling point of water, is

asked Aug 21, 2018 by pady_1

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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?

In the combination of the following gates the output Y can be written in terms of inputs A and B as <br>

In a p-n junction diode, change in temperature due to heating

In the circuit shown in the figure, the input voltage $V_i$ is 20 V, $V_{BE}$ = 0 and $V_{CE}$ = 0. The value of $I_B, \; I_C$ and $\beta$ are given by <br>

The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance

An em wave id propagating in a medium with a velocity $\overrightarrow{V} = V \hat{i}$. The instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along

An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm. If the object is displaced through a distance of 20 cm towards the mirror, the displacement of the image will be :

An inductor 20 mH, a capacitor $100 \; \mu F$ and a resistor $50 \Omega$ are connected in series across a source of emf, $V = 10 \sin 314 \;t$. The power loss in the circuit is

Current sensitivity of a moving coil galvanometer is 5 div/mA and its voltage sensitivity (angular deflection per unit voltage applied ) is 20 div/V. The resistance of the galvanometer is

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 :

A carbon resistor of $(47 \pm 4.7) \; k \Omega$ is to be marked with rings of different colours for its identification. The colour code sequence will be :

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 ?

The volume (V) of a monatomic gas varies with its temperature (T), as shown in the graph. The ratio of work done by the gas, to the heat absorbed by it, when it undergoes a change from state A to state B, is <br>

The fundamental frequency in an open organ pipe is equal to the third harmonic of a closed organ pipe. If the length of the closed organ pipe is 20 cm, the length of the open organ pipe is :

At what temperature will the rms speed of oxygen molecules become just sufficient for escapig from the Earth's atmosphere ? <br> (Given : <br> Mass of oxygen molecule (m) = $2.76 \times 10^{-25} kg$ <br> Boltzmann's constant $(K_B) = 1.38 \times 10^{-23} JK^{-1}$ )

The effciency of an ideal heat engine workong between the freezing point and boiling point of water, is